The Oil Filter discussion thread.

In order to keep the WDYDT thread uncluttered, I think this is where oil filter discussion should happen.

 

There is quite a bit to be said about filters, but I'll start with this as its one thing I never put any thought into but seems to be a very big deal.

 

I believe it is very important, if not most important, that you choose a filter with the proper 23psi bypass valve setting. Anytime your oil is bypassing the filter its like not even having a filter. Here is a note I found on a filter website, "GM recommends this part number for specific applications that require a pressure relief valve opening pressure setting of 22 PSI. For comparison, X2222 and S2222 are both direct replacements of ACDelco PF48/PF48E, which features a pressure relief valve that is set to open at 15 PSI." with another note of "Incorrect use of these oil filters may result in premature engine wear and costly repairs." When Subaru switched from Tokyo Roki to Fram they had Fram bring their bypass valve spec up to 23psi to meet the required spec.

 

If you're going for extended OCI, you should be using an extended OCI (or synthetic) filter or replacing your filter even if you keep the same oil as the collection of particles will increase the Delta P and cause the bypass to open.

 

Additionally its good to have an Anti-Drainback valve to prevent dry startups.

 

I had originally decided on Wix XP Synthetic filters but I think I will switch over to the Maza Tokyo's because they're taller with more media. While its not required - I think its a good thing to have more media surface area.

 

And now let the debate flood gates open!

I've been running the Quaker State QS14612 that I can get here, I'm 99% sure they are made by purolator, nothing but good things to say about them so far. No failures and no engine problems.

Haha ok I'll try my hand at this. Really I may have the means to do some filter testing possibly with unused filters on the media. I think there are probably a lot of stuff on the market, like the ones amsoil says you should use on the subaru (note that it's not the EA15k13) that claims to have a bypass but not at the stated PSI.

 

With some searching, you can find that the theory has been pretty beat to death. I don't know if anyone has answered why the 23psi bypass is so high (people claim it is higher than many cars. I don't honestly know this) but the thought is because the oil pump puts out a very high volume at max load. There is also debate as to whether or not the oil pump regularly hits those loads as most of the stuff I find is theory. We do however have multiple members who run oil pressure gauges so maybe we could see what is normal in the system, from different points on the engine, and kinda figure out what is really needed vs what is called for. Because remember, subaru called for filters in the banjo bolts.

 

Most of the theory threads seem to be inhabited by people who don't own turbo subarus or aren't doing oil analysis on their vehicles. So more so than is a 23 psi needed, I'd like to see something more like https://web.archive.org/web/20050311162313/http://www.oilfilterstudy.com/ on filters for our cars. Of course willing to input my time and whatever access to stuff I have.

 

To note though, I am not an engineer, or a chemist, nor do I really understand oil. Also I realize this probably doesn't really matter THAT much at the end of the day. Not trying to get long oil change intervals or more engine life. Just my own curiosity.

I’ve been using Purolator Boss filters for the last few years. The bypass PSI on their website reads a generous range of 20-30psi. Although the filter is good for 15k miles I usually set my intervals still at 3500 miles just to be on the safe side.

Haha ok I'll try my hand at this. Really I may have the means to do some filter testing possibly with unused filters on the media. I think there are probably a lot of stuff on the market, like the ones amsoil says you should use on the subaru (note that it's not the EA15k13) that claims to have a bypass but not at the stated PSI.

 

With some searching, you can find that the theory has been pretty beat to death. I don't know if anyone has answered why the 23psi bypass is so high (people claim it is higher than many cars. I don't honestly know this) but the thought is because the oil pump puts out a very high volume at max load. There is also debate as to whether or not the oil pump regularly hits those loads as most of the stuff I find is theory. We do however have multiple members who run oil pressure gauges so maybe we could see what is normal in the system, from different points on the engine, and kinda figure out what is really needed vs what is called for. Because remember, subaru called for filters in the banjo bolts.

 

Most of the theory threads seem to be inhabited by people who don't own turbo subarus or aren't doing oil analysis on their vehicles. So more so than is a 23 psi needed, I'd like to see something more like https://web.archive.org/web/20050311162313/http://www.oilfilterstudy.com/ on filters for our cars. Of course willing to input my time and whatever access to stuff I have.

 

To note though, I am not an engineer, or a chemist, nor do I really understand oil. Also I realize this probably doesn't really matter THAT much at the end of the day. Not trying to get long oil change intervals or more engine life. Just my own curiosity.

 

I too am curious about how often the bypass is triggered both new and over the life of a filter but I do believe it would require two gauges strategically placed for accurate readings at the filter.

 

I do think whats being discussed is quite important but sometimes people get caught up in the little things. Its not like we're talking about a cabin air filter - the oil and oil filter are important to the life of the vehicle. And while theres no single "best" filter, its nice to be aware of differences and what to be aware of or think of while shopping.

 

Yeah, Subaru also recommended coolant additive because of the head gasket issue and put cats in the up pipe... but mfg bashing aside - Subaru isnt the only company to recommend a specific PSI bypass. GM has a requirement about it and the filter company (Ecoguard) also had notes about improper filter bypass spec. So I do think theres more to it then the standard "Only use Subaru approved products" jargon and it seems like some filters listed as "OEM replacement" dont actually have the right bypass spec.

 

I pulled this from the WDYDT thread:

i did filter life testing when i first started my job. but it all depends on what you think is important. do you want EVERYTHING filtered out? are you ok with changing the filter every month? can it be giant, so you don't have to change it every month? What's your price point? do you really care about 5 micron particles?

 

We (where i work) don't care about sub-7 micron particles, and we deal with some VERY precise and small fluid paths (and a TON of them), so i'd venture to guess that a Subaru engine doesn't care either...

 

the main issue with anything is you can't design/make it to please everyone.

 

the filters are made to Subaru spec, and for a good cost. Subaru gets exactly what they ask for.

 

The Brotella Brothers think their STI needs to run on pure, cold-filtered cheetah blood. they don't like OEM filters.

 

There are filters that are "worse" than the OEM filters, and there are probably some that are better. does that "better" make a difference? is it worth the cost?

 

Which has a good point - theres no single best filter - you need the filter that best fits your intentions. The filter thats best at filtering would not be the filter for long OCI unless you plan on swapping filters often for the same oil or having a massive filter able to withstand high levels of filtration for extended periods of time.

Edited November 9, 2019 by Sparkey

Well it wasn't so much meant as mfg bashing as it was a just because it's needed in some cases doesn't mean it's needed in all. I'm sure there's a reason they put filters in the banjo bolts. And I know why they put cats in the up pipe and why they run an open closed loop delay.

 

The point was more, if most of your driving is in relatively warm temperatures, on the highway, and calm, like say someone long distance commuting in Texas, well you can probably get away with a lower oil bypass psi since most of your driving is at low throttle with decent oil temperature and lower end of rpm. But if most of your driving is up canyons in the winter and you like to push it, then maybe you need the higher psi that is called for.

 

The thing that's best for long oci is apparently an oil bypass set up like gets used on semis. But they are relatively expensive and not really worth it for the normal person. The next best thing is done testing with filters of choice and Blackstone. Because they are monitoring wear and oil shear and things like that.

 

 

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I think most people are fine doing 3750 oci synthetic per subarus recommendation. Honestly I'm pretty OK using oe filters blue or black. Lots of people use them on lots of vehicles with no issues. I don't think I've ever seen oil starvation attributed to a filter unless it got knocked off the vehicle or oil contamination if it wasn't pushed way beyond oci recommendation.

 

So the question, imo, becomes what's better. Is the oem filter good enough for most applications? Does using a high level of filtration effect oil pressure over the course of the oci, or extended oci (almost certainly not. Wouldn't make a good product if it did) Are there measurable differences that matter in the levels of filters?

 

The last question makes me think of covertrussians last post on inlet pressure drops. I'm still trying to sort out if that difference matters. Like if you're trying to catch every last little bit of perfection then yes but is the difference in the blue subaru filter, the Mazda filter, and the amsoil filter enough to make me go out of my way?

Also I'm going to hypothesize that these small differences don't add up to much in all honesty. It's not the thing that kills our cars. But I still want to know if cheetah blood will make my engine 0.005% less likely to explode.

 

 

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I'll drop an older discussion into this thread as well. It's a long read, but hey, if you're bored..

https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1410171

 

I joined bitog in 2004, and I've been an oil and filter geek for a long time. I used to care a lot about this kind of thing. Over the years I've started to realize something though, it really doesn't matter anymore in most cars. Since this is a discussion about filters, I'll try to stick to filters, but it's hard.

 

I will only use a filter which meets Subaru's bypass valve spec, they are very easy to find these days. Fram, wix, napa, purolator, oem subaru, all the big name companies now make a filter that meets that spec, there is no reason not to in my opinion. I've heard that high insolubles on a used oil analysis is one way to determine if a filter is overloaded, and not doing its job anymore. I've never seen a Subaru uoa with high insolubles to suggest that the small filter on our cars is insufficient.

 

With that said, I don't think it's the end of the world if someone runs a filter that doesn't meet the bypass valve spec. Your oil may be bypassing the filter media more often in certain situations, but it is still getting filtered. How often does all of the oil, or some of the oil go through the filter? Hard to say, a number of factors are involved in that.

 

As far as an anti-drainback valve, I think all filters for our cars come with one, since the oem Subaru filter specs one. I think that's one area where aftermarket filters won't deviate from oem. If oem has an adbv (anti-drainback valve), the aftermarket filter will too. There could be exceptions to that, but I'd be surprised if there were.

I'll drop an older discussion into this thread as well. It's a long read, but hey, if you're bored..

https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1410171

 

I tried reading through this a few days ago actually, and when gary and superbusa start going at it, I just can't even follow what's happening actually. A lot of arguing about theoretical max flow of the oil pump and whether the high bypass is needed and if it's there because of the pump from what I could tell. I don't know if it gets more informative later on.

 

It seems to me that the reason everyone said to run OEM filters for a long time is that bypass spec. But with many options that have that spec, what's really the difference in the filters. Outside of a few ones making claims about levels of filtration, I can't seem to find any real information. There are pictures of things cut open, complaints about cardboard, and comments that black tokyo roki filters are better than blue fram/honeywell filters because something.

 

I don't care if it's cardboard or fairy dust filtering the oil, as long as they both filter properly over the intended OCI interval. Maybe I'll try going through that thread again and I'll pick up something I missed.

I think most people are fine doing 3750 oci synthetic per subarus recommendation. Honestly I'm pretty OK using oe filters blue or black. Lots of people use them on lots of vehicles with no issues. I don't think I've ever seen oil starvation attributed to a filter unless it got knocked off the vehicle or oil contamination if it wasn't pushed way beyond oci recommendation.

 

So the question, imo, becomes what's better. Is the oem filter good enough for most applications? Does using a high level of filtration effect oil pressure over the course of the oci, or extended oci (almost certainly not. Wouldn't make a good product if it did) Are there measurable differences that matter in the levels of filters?

 

The last question makes me think of covertrussians last post on inlet pressure drops. I'm still trying to sort out if that difference matters. Like if you're trying to catch every last little bit of perfection then yes but is the difference in the blue subaru filter, the Mazda filter, and the amsoil filter enough to make me go out of my way?

 

When you say better, what do you want it to be better at? Extended OCI filters have bigger micron ratings then standard filters - both will work fine but ones better at filtering and ones better at not having to be changed as often.

 

Sort of spitballing here so im not sure but this is my thought.

 

You shouldnt see starvation due to the bypass. You would have to have a clogged filter and failed bypass for the oil filter to cause starvation. Im mostly concerned with the oil actually being filtered and not bypassing it. As with the banjo filters being clogged - in theory that shouldnt happen because it should have been trapped in the filter right? So if enough particles are passing through to the banjo filters to clog them, it seems the bypass opens often. What if people using non oem spec filters is what helped contribute to the filters being clogged? If the bypass is half the psi, your filtering only half as much because the bypass is open more.

 

Pressure increases over time with the filter catching more particles. When a fuel filter clogs you see pressure drop and a dirty air filter doesnt pull as much air. Its why Injector Dynamics put a gauge on their fuel filter and Ford put one on their 'lifetime' air filter.https://www.ecogard.com/fuel-filter-101-symptoms-replacement-cost/

 

From those three filters you could go with whats cheapest and be fine - but thats mostly because theyre all subaru spec filters.

 

Also I'm going to hypothesize that these small differences don't add up to much in all honesty. It's not the thing that kills our cars. But I still want to know if cheetah blood will make my engine 0.005% less likely to explode.

 

 

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Yes and no. It only takes one bad lean event to take out an engine. And while using a wrong spec filter once may not be bad, continued use could slowly take out an engine. I feel like if the filter did its job well enough 100% of the time the banjos never had clogged. Maybe the solution to failed turbos was actually a symptom of incorrect spec filters?

 

I'll drop an older discussion into this thread as well. It's a long read, but hey, if you're bored..

https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1410171

 

I joined bitog in 2004, and I've been an oil and filter geek for a long time. I used to care a lot about this kind of thing. Over the years I've started to realize something though, it really doesn't matter anymore in most cars. Since this is a discussion about filters, I'll try to stick to filters, but it's hard.

 

I will only use a filter which meets Subaru's bypass valve spec, they are very easy to find these days. Fram, wix, napa, purolator, oem subaru, all the big name companies now make a filter that meets that spec, there is no reason not to in my opinion. I've heard that high insolubles on a used oil analysis is one way to determine if a filter is overloaded, and not doing its job anymore. I've never seen a Subaru uoa with high insolubles to suggest that the small filter on our cars is insufficient.

 

With that said, I don't think it's the end of the world if someone runs a filter that doesn't meet the bypass valve spec. Your oil may be bypassing the filter media more often in certain situations, but it is still getting filtered. How often does all of the oil, or some of the oil go through the filter? Hard to say, a number of factors are involved in that.

 

As far as an anti-drainback valve, I think all filters for our cars come with one, since the oem Subaru filter specs one. I think that's one area where aftermarket filters won't deviate from oem. If oem has an adbv (anti-drainback valve), the aftermarket filter will too. There could be exceptions to that, but I'd be surprised if there were.

 

My theory is the bypass is open during high demand which is the same time you have the highest flow and theres the possibility you can pump all of the oil though in that short time. So even if its an event that doesnt happen often, when it does its at its most likely condition for something to go wrong.

 

Here is some info about the advancements in filtration allowing filters to be smaller. https://www.ecogard.com/explaining-concept-oil-filter-consolidation-customers/ even still, i like the longer filter for a little easier install if nothing else.

 

After typing all that I found this thread: https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/309758/2 seems like the bypass opens far more then I expected. So im for doing any and everything to be sure I filter the oil as often as possible.

 

I think it would be interesting to see the same oil used on two identical filters but with different bypass spec. Then do a UOA and have the filters analyzed.

I tried reading through this a few days ago actually, and when gary and superbusa start going at it, I just can't even follow what's happening actually. A lot of arguing about theoretical max flow of the oil pump and whether the high bypass is needed and if it's there because of the pump from what I could tell. I don't know if it gets more informative later on.

 

It seems to me that the reason everyone said to run OEM filters for a long time is that bypass spec. But with many options that have that spec, what's really the difference in the filters. Outside of a few ones making claims about levels of filtration, I can't seem to find any real information. There are pictures of things cut open, complaints about cardboard, and comments that black tokyo roki filters are better than blue fram/honeywell filters because something.

 

I don't care if it's cardboard or fairy dust filtering the oil, as long as they both filter properly over the intended OCI interval. Maybe I'll try going through that thread again and I'll pick up something I missed.

 

Basically Fram has some failures that ruined their rep as Fram and some of the first blue filters were recalled so people stuck with what worked - the black ones. Then people search the internet and find outdated info but continue to apply it. Like you said, the construction is irrelevant if it works, then it works. But others like myself do feel more comfortable with metal construction - which from looking at some of the top thread blue subie filters they look to be taller and with metal caps? Ive not checked into that yet tho.

 

Without extensive testing the theorys behind extra filter media and such are just theories. Two filter medias of totally different thickness, composition, and length can perform the exact same. But its not a major price difference and I at least feel like im providing more then adequate oil and filtration with filters and companies that seem to have more media.

 

I also found some people who had specs on the holes in the center tubes and were discussing flow rates. I think that topic is far more touchy as that then could be dependent on your filter media. Some media may require slower filtration - is it too slow for the bypass and causing it to open more then normal?

I use napa gold 7055 (wix). It's the longer filter with a high bypass. I have no leaks from the filter and they never loosen over time.

I use NAPA Gold for the 2001 Miata, but the taller one for the Millenia rather than the short one specified for the Miata. It seems to be the perfect choice for that application because the Miata is very gentle on its oil and the metal end caps and thread-end bypass were exactly what I prefer.

 

I specifically went away from NAPA filters for the Subaru because several years ago I used one that kept loosening. The vibration in a flat four engine is rotational about a vertical axis and the filter mounts vertically, so there are forces that promote loosening. My concern was that the threads on the filter were on the large side of tolerance and not holding properly. I had no such problem with any other filter.

 

Many years ago, drag racer Smokey Yunick used to use oil filter adaptors that had four filters in parallel. That way, the bypasses would never open and the filtration area was sufficient for drag race engines running up into unholy rev ranges. It is worth a thought.

Its been fourteen years this kind of topic came up on any legacy gt forum tread.

 

Its lives on...

 

i use SuperTech St 6607 for the the filter.

Edited November 10, 2019 by ttnio

It's worth considering the sizes of the filters. The larger filters have more area, therefore take longer to clog up and less restriction on flow, thereby reducing pressure drop due to the filter.

 

Note the short STI/LGT filter vs the larger Outback filter. I run the Purolator Boss, Mobil One and the larger Subaru OEM filter depending what's on sale. They all fit on my race cars because I've removed the Oil/coolant heater/cooler that makes the filter hang down so low.

 

The Purolator Boss splits the difference between the short OEM size filters and the longer OEM and Mobile 1 filter.

 

I estimate the taller filters have about 30% more filter media area. The Purolator Boss and Mobil 1 have significantly heavier duty construction than any of the other filters. And they claim higher burst strength because of it. For me it's important that when hopping over apex curbs and the occasional off track excursions that the filter have an extra margin of puncture/tear/dent resistance.

 

I did a comparison a while ago, here you go in pics:

 

Edited November 14, 2019 by Sgt.Gator

It's worth considering the sizes of the filters. The larger filters have more area, therefore take longer to clog up and less restriction on flow, thereby reducing pressure drop due to the filter.

 

Note the short STI/LGT filter vs the larger Outback filter. I run the Purolator Boss, Mobil One and the larger Subaru OEM filter depending what's on sale. They all fit on my race cars because I've removed the Oil/coolant heater/cooler that makes the filter hang down so low.

 

The Purolator Boss splits the difference between the short OEM size filters and the longer OEM and Mobile 1 filter.

 

I estimate the taller filters have about 30% more filter media area. The Purolator Boss and Mobil 1 have significantly heavier duty construction than any of the other filters. And they claim higher burst strength because of it. For me it's important that when hopping over apex curbs and the occasional off track excursions that the filter have an extra margin of puncture/tear/dent resistance.

 

I did a comparison a while ago, here you go in pics:

 

 

 

From: https://www.ecogard.com/explaining-concept-oil-filter-consolidation-customers/

 

"The paper media in today’s filter elements are more advanced, with the ability to capture more dirt than they used to. This translates to less paper in the finished filter and ultimately allows aftermarket manufacturers to reduce the size of the canisters."

 

But when comparing two filters of the same media, like the two blue subaru filters, yes, the filter of larger area would be better. However, supposedly they use the smaller one to help limit heat transfer on turbo models however. But then if you get an oil filter heat blanket then it doesnt matter

I run the larger Amsoil Filter - EA15K13

 

Interestingly enough - Amsoil filters run a lower bypass 11 -17 PSI on all filters - so high bypass may not always be the answer?

 

Although I would think they've at least generally researched appropriate bypass levels since they are sponsoring race cars and such?

 

Amsoil Filter Specs

I run the larger Amsoil Filter - EA15K13

 

Interestingly enough - Amsoil filters run a lower bypass 11 -17 PSI on all filters - so high bypass may not always be the answer?

 

Although I would think they've at least generally researched appropriate bypass levels since they are sponsoring race cars and such?

 

Amsoil Filter Specs

 

Race cars are just rolling advertisements and usually run far different components then off the shelf stuff https://mobiloil.com/en/article/car-maintenance/basic-car-maintenance-tips/different-types-of-oil-filters-and-how-they-work

 

I guess there might be a combination of thinner oil with a higher flow filter that would need a lower bypass? I cant really think of a situation that would call for a lower bypass then spec without decreasing flow.

 

I may reach out to a few companies and see what they say... but after more reading I think I want a heated bypass filter for 2 micron filtration and to remove water and fuel contaminants. didnt HAMMERDOWN have a dual filter bypass system and make it nearly 350k?

For my 2006 NA Outback I usually run a Wix/Napa Gold as it is one of the few that meets the OEM bypass spec and has decent specs with its' syn blend filter media. 5-7500 OCI.

 

Or a Fram Ultra for the hard to beat filtering specs and constructing. Run this filter for 1 year/2 5000 OCIs. It could go longer I'd say, but I don't like leaving a single oil filter on for the 2 years it takes that car to hit 15000 miles.

I've been using Mobil 1 filters because hey are a discount deal with Mobil1 oil (extended performance). That being said, the filter and oil are always changed well within a very conservative interval. Why would you leave dirty oil in the engine and worry about gumming up the banjo bolts?

And can someone tell me about the benefits of an anti-drainback valve on a filter used in a Subaru? If the filter is hanging upside down off the engine, wouldn't gravity take care of making sure the filter is always full?

And can someone tell me about the benefits of an anti-drainback valve on a filter used in a Subaru? If the filter is hanging upside down off the engine, wouldn't gravity take care of making sure the filter is always full?

 

It keeps the oil up in the engine block passages, hopefully right up to the main bearings so as soon as you crank the engine the bearings are getting oil pressure.

HI guys I completely rebuilt my 05 OBXT motor (At 139000 due to 2 turbos fragging and bypassing the oil filter with the previous owner) Any way did lots of research and filter I am using is a wix 51287 out of a Porsche 944. It is only slightly bigger in diameter but lots taller and has a 29psi bypass. the inherent problem with these motors is that because of the aluminum block the main bearing clearance opens up a great deal when the engine warms up so they often have 100 psi or more when they are cold and Will BYPASS if revved when cold.I have oil temp and oil pressure gauges.the oil can take 10 miles to warm up in he winter. 0w40 mobil 1 has worked well for me. They deffinently need 0 in the first number at any rate . Just my 2 cents.this filter is probably to tall for lowered cars works great on stock height outbacks

And can someone tell me about the benefits of an anti-drainback valve on a filter used in a Subaru? If the filter is hanging upside down off the engine, wouldn't gravity take care of making sure the filter is always full?

 

As Sgt. Gator pointed out, its more then just the filter - if its not allowed to drain back it should keep the passages full an prevent dry starts.

 

I run the larger Amsoil Filter - EA15K13

 

Interestingly enough - Amsoil filters run a lower bypass 11 -17 PSI on all filters - so high bypass may not always be the answer?

 

Although I would think they've at least generally researched appropriate bypass levels since they are sponsoring race cars and such?

 

Amsoil Filter Specs

 

I sent out some e-mails and such to manufacturers...

 

Amsoil seems to contradict themselves.

 

"All of our filters meet the bypass valve pressure relief settings that the OEM calls for. Most of our filters are 11-17psi but some have 18-24psi levels to meet the standards that are set, or else we would be able to recommend our filters for use.

 

The bypass setting will make the oil filter through center tube only if the pressure in the filter reaches the set psi. If this didn't happen then the oil filter would swell up and explode. The only time you would want a lower setting than OEM would be to not put as much pressure on the filter itself."

 

By their filter chart they dont make a correct filter, so I asked for clarification.

 

"The 23 psi would be referring to that would be the max pressure the filter can see before entering bypass mode. Since our filters would enter bypass mode before then 11-17 psi it is below 23 psi that the factory expresses so it makes the filter suitable for use."

 

I believe they just dont want to have as many SKU's as they should have and thus use lower bypass filters so the one filter fits many more applications... that or they just dont make a filter that can handle factory pressures

 

Spoke to Fram and this is what they had to say:

 

Me 09:58

Hello, I am curious about oil filter bypass valve spec and what happens if the filter spec isnt what the OEM calls for?

Donald 09:59

The by pass valve operates on a pressure difference between inside the filter media and outside the filter media. They claim that is the wrong spec is used it could by pass when it is not supposed to and not filter the oil.

Is there anything else I can help you with?

Me 10:02

When you say "they claim", are you saying they're wrong? Because that sounds bad if my oil filter is getting bypassed

Donald 10:03

No. I am not saying they are wrong. It would be bad if it is not getting filtered.

Me 10:05

So it is bad to run a filter with a lower then OEM spec.

Read

Donald 10:06

Yes it could lead to engine damage.

 

And when you look up filters they really only recommend one for turbo applications "Based on OE Specification". The other ones are transmission filters and used for N/A applications - more on that to come...

 

I'm still talking with Ecoguard because they seem to state N/A's use a lower bypass then Turbos which contradicts the factory manuals. Heres what they had to say:

 

"The filter’s by-pass valve is a safety measure to allow oil to circulate through the engine to ensure the engine is not starved of oil when the filter is clogged or when the oil is cold and thick during startup. The basic premise of the by-pass valve is that it is better to have dirty oil in the engine than to have no oil at all.

 

In conjunction, the by-pass valve opening pressure setting is very important for the longevity of the engine. If the by-pass valve opens at lower pressure than intended by the engine manufacturer, the valve could be in the open position during normal operation allowing dirty oil to wear down engine components at a much greater rate. The key for every filter with a by-pass valve is to have the opening pressure set higher than the differential pressure created by normal operating pressure of the vehicle.

 

Many Subaru models, including your Legacy GT, have their oil lubrication system operating at higher pressure than most common vehicles on the road. The higher differential pressure created by the Subaru engines require the filter’s by-pass valve to be set to open at higher pressure in order to prevent the valve from opening too soon and remaining opened for extended period of time. Similar-sized filters designed for other vehicles like Hondas, Nissans, etc. have their opening pressure set lower at about 12PSI which is not appropriate for most Subarus.

 

The ECOGARD oil filter X4615 is specifically designed for Subaru applications with a by-pass valve set to open at 23PSI. If you change your oil and filter beyond 5,000 miles, we recommend the ECOGARD part number S4615 which has the same by-pass valve and is designed for oil changes up to 10,000 miles.

 

I hope the above explanation gives you confidence in your understanding of the by-pass valve and the importance of opening settings."

 

I looked at their reference chart and they listed one filter as a "Velocity option" which is the one rockauto lists for all Subaru applications. I also asked what they would recommend if I ran synthetic but only for 3500 miles.

 

"Do you have the non-turbo 2.5L Legacy? If so, the S4612 is the correct oil filter for your vehicle. The non-turbo engines do not require the higher-set by-pass valve.

 

 

 

If you have the turbo 2.5L, the S4615 is the correct oil filter due to the 23PSI by-pass valve requirement.

 

 

 

The Velocity Option means that filter has a smaller can diameter than the original filter and thus will fit more vehicles. The Velocity Option’s critical dimensions and components like the gasket, by-pass valve, drain-back valve, etc. match the original filter, so it performs as intended in the vehicle. The only difference between the original and the Velocity Option will be the amount of filter media inside and thus total amount of dirt the filter can hold. This does not affect the function of the filter at all if changed at 5,000 miles or less.

 

 

 

To be clear, the S4612 is not an option if you have the turbo and require the S4615. The original filter for the non-turbo Legacy is the ECOGARD X4460.

 

 

 

As far as using synthetic oil and keeping change interval at 3,500 miles, we would always recommend the S filter over the X. The S filter uses a synthetic blend media that holds more dirt and filters out smaller particles to better protect modern engines. Today’s filtration technology allows us to build filters with great filtration properties without sacrificing flow of oil.

 

 

 

To summarize: if you have the non-turbo Legacy, the S4612 is a great filter for you. If you have the turbo Legacy, you’ll want to use the S4615."

 

So now I've sent an inquiry stating that all Subaru's factory service manuals call out a 23PSI bypass on the filter. And all the pump specs are very similar even with the rotor width being different. So I've asked where they got their information from for the N/A filter specs or why it would be different if the pump output is the same?

 

I always though the 11 and 12mm pumps would flow more and such but im not sure thats true if a 9 and 10mm flow the same.

As Sgt. Gator pointed out, its more then just the filter - if its not allowed to drain back it should keep the passages full an prevent dry starts.

 

 

 

 

 

 

 

I sent out some e-mails and such to manufacturers...

 

 

 

Amsoil seems to contradict themselves.

 

 

 

"All of our filters meet the bypass valve pressure relief settings that the OEM calls for. Most of our filters are 11-17psi but some have 18-24psi levels to meet the standards that are set, or else we would be able to recommend our filters for use.

 

 

 

The bypass setting will make the oil filter through center tube only if the pressure in the filter reaches the set psi. If this didn't happen then the oil filter would swell up and explode. The only time you would want a lower setting than OEM would be to not put as much pressure on the filter itself."

 

 

 

By their filter chart they dont make a correct filter, so I asked for clarification.

 

 

 

"The 23 psi would be referring to that would be the max pressure the filter can see before entering bypass mode. Since our filters would enter bypass mode before then 11-17 psi it is below 23 psi that the factory expresses so it makes the filter suitable for use."

 

 

 

I believe they just dont want to have as many SKU's as they should have and thus use lower bypass filters so the one filter fits many more applications... that or they just dont make a filter that can handle factory pressures [emoji38]

 

 

 

Spoke to Fram and this is what they had to say:

 

 

 

Me 09:58

 

Hello, I am curious about oil filter bypass valve spec and what happens if the filter spec isnt what the OEM calls for?

 

Donald 09:59

 

The by pass valve operates on a pressure difference between inside the filter media and outside the filter media. They claim that is the wrong spec is used it could by pass when it is not supposed to and not filter the oil.

 

Is there anything else I can help you with?

 

Me 10:02

 

When you say "they claim", are you saying they're wrong? Because that sounds bad if my oil filter is getting bypassed

 

Donald 10:03

 

No. I am not saying they are wrong. It would be bad if it is not getting filtered.

 

Me 10:05

 

So it is bad to run a filter with a lower then OEM spec.

 

Read

 

Donald 10:06

 

Yes it could lead to engine damage.

 

 

 

And when you look up filters they really only recommend one for turbo applications "Based on OE Specification". The other ones are transmission filters and used for N/A applications - more on that to come...

 

 

 

I'm still talking with Ecoguard because they seem to state N/A's use a lower bypass then Turbos which contradicts the factory manuals. Heres what they had to say:

 

 

 

"The filter’s by-pass valve is a safety measure to allow oil to circulate through the engine to ensure the engine is not starved of oil when the filter is clogged or when the oil is cold and thick during startup. The basic premise of the by-pass valve is that it is better to have dirty oil in the engine than to have no oil at all.

 

 

 

In conjunction, the by-pass valve opening pressure setting is very important for the longevity of the engine. If the by-pass valve opens at lower pressure than intended by the engine manufacturer, the valve could be in the open position during normal operation allowing dirty oil to wear down engine components at a much greater rate. The key for every filter with a by-pass valve is to have the opening pressure set higher than the differential pressure created by normal operating pressure of the vehicle.

 

 

 

Many Subaru models, including your Legacy GT, have their oil lubrication system operating at higher pressure than most common vehicles on the road. The higher differential pressure created by the Subaru engines require the filter’s by-pass valve to be set to open at higher pressure in order to prevent the valve from opening too soon and remaining opened for extended period of time. Similar-sized filters designed for other vehicles like Hondas, Nissans, etc. have their opening pressure set lower at about 12PSI which is not appropriate for most Subarus.

 

 

 

The ECOGARD oil filter X4615 is specifically designed for Subaru applications with a by-pass valve set to open at 23PSI. If you change your oil and filter beyond 5,000 miles, we recommend the ECOGARD part number S4615 which has the same by-pass valve and is designed for oil changes up to 10,000 miles.

 

 

 

I hope the above explanation gives you confidence in your understanding of the by-pass valve and the importance of opening settings."

 

 

 

I looked at their reference chart and they listed one filter as a "Velocity option" which is the one rockauto lists for all Subaru applications. I also asked what they would recommend if I ran synthetic but only for 3500 miles.

 

 

 

"Do you have the non-turbo 2.5L Legacy? If so, the S4612 is the correct oil filter for your vehicle. The non-turbo engines do not require the higher-set by-pass valve.

 

 

 

 

 

 

 

If you have the turbo 2.5L, the S4615 is the correct oil filter due to the 23PSI by-pass valve requirement.

 

 

 

 

 

 

 

The Velocity Option means that filter has a smaller can diameter than the original filter and thus will fit more vehicles. The Velocity Option’s critical dimensions and components like the gasket, by-pass valve, drain-back valve, etc. match the original filter, so it performs as intended in the vehicle. The only difference between the original and the Velocity Option will be the amount of filter media inside and thus total amount of dirt the filter can hold. This does not affect the function of the filter at all if changed at 5,000 miles or less.

 

 

 

 

 

 

 

To be clear, the S4612 is not an option if you have the turbo and require the S4615. The original filter for the non-turbo Legacy is the ECOGARD X4460.

 

 

 

 

 

 

 

As far as using synthetic oil and keeping change interval at 3,500 miles, we would always recommend the S filter over the X. The S filter uses a synthetic blend media that holds more dirt and filters out smaller particles to better protect modern engines. Today’s filtration technology allows us to build filters with great filtration properties without sacrificing flow of oil.

 

 

 

 

 

 

 

To summarize: if you have the non-turbo Legacy, the S4612 is a great filter for you. If you have the turbo Legacy, you’ll want to use the S4615."

 

 

 

So now I've sent an inquiry stating that all Subaru's factory service manuals call out a 23PSI bypass on the filter. And all the pump specs are very similar even with the rotor width being different. So I've asked where they got their information from for the N/A filter specs or why it would be different if the pump output is the same?

 

 

 

I always though the 11 and 12mm pumps would flow more and such but im not sure thats true if a 9 and 10mm flow the same.

 

At least Fram's explanation of how the bypass works is correct.