Oil change intervals synthetic vs. conventional

I have the 3.6. I am at the 30,000 mile mark and the dealership wants to charge me the insane $500 for the service. Not about to do that. In looking, the only 3 things the scheduled maintenance calls for replacing is the brake fluid change, the oil change and the filter change. Everything else is just an inspection. Here's my question. The manual calls for a 6,000 mile interval on oil and filter change. The service writer says that only for the conventional oil in the 4 cyl. engine and that the 3.6 calls for a 3,000 mile interval. I'm calling "BS". I can't see any differences spelled out in the book. It simply shows 6K intervals, making no differences between oil types and the interval. Did I miss something? Is he right by the book?

... filter change ...

 

To clarify: At 30,000 miles, the Warranty & Maintenance Guide calls for changing both the engine oil filter and the engine intake air filter.

 

The manual calls for a 6,000 mile interval on oil and filter change. The service writer says that only for the conventional oil in the 4 cyl. engine and that the 3.6 calls for a 3,000 mile interval.

Bulldust !!! on multiple counts: 1) The 0W-20 oil specified for the H4 is only available in synthetic. 2) Neither the Warranty & Maintenance Guide nor the Factory Service Manual call for 3,000 mile oil change intervals (conventional or synthetic) for either engine except under "severe driving conditions", further defined as "Repeated short distance driving," "Driving in extremely cold weather," and/or "Repeated trailer towing."

Personally, unless it's a warranty issue I never go to a dealer for service. Their prices are usually insane and from my experience they aren't the most knowledgeable. As it seems to be in your case.

Agreed. I currently do go to my dealer but I have free oil changes to 25K. I asked last time for synthetic and they agreed. My next appt. is this Friday and I asked again about the oil and they said they use a "synthetic blend". I'm not aware of a Subaru PN for a blend? I thought they had 5W-30 in either conventional or full synthetic only.

Agreed. I currently do go to my dealer but I have free oil changes to 25K. I asked last time for synthetic and they agreed. My next appt. is this Friday and I asked again about the oil and they said they use a "synthetic blend". I'm not aware of a Subaru PN for a blend? I thought they had 5W-30 in either conventional or full synthetic only.

 

I'm pretty sure almost all oils are some type of synthetic blend these days. Unless you pay for a full synthetic (hence the term "full"), it's almost certainly a blend.

 

Personally, unless it's a warranty issue I never go to a dealer for service. Their prices are usually insane and from my experience they aren't the most knowledgeable. As it seems to be in your case.

 

Eh, it's hit or miss. If you sound like you know what you're talking about and don't like the response from the writer you're getting, you can request a senior tech to discuss your car. You might have to wait a bit for one, but that's what the free coffee and bagels are for...

 

I have the 3.6. I am at the 30,000 mile mark and the dealership wants to charge me the insane $500 for the service. Not about to do that. In looking, the only 3 things the scheduled maintenance calls for replacing is the brake fluid change, the oil change and the filter change. Everything else is just an inspection. Here's my question. The manual calls for a 6,000 mile interval on oil and filter change. The service writer says that only for the conventional oil in the 4 cyl. engine and that the 3.6 calls for a 3,000 mile interval. I'm calling "BS". I can't see any differences spelled out in the book. It simply shows 6K intervals, making no differences between oil types and the interval. Did I miss something? Is he right by the book?

 

You have the 3.6, so you're correct. Your engine, the EZ36D, can take the conventional 5w30 oil; however, the manual recommends synthetic. That should be listed somewhere in the "Specifications" section of your manual. Also note, that the 3.6 engine takes close to 7 quarts of oil; there's usually a price surcharge with that, and the "19.95!!!!" oil changes you see flaunted have a little asterisk that says "6 cylinders extra" - because you'll need about 2-3 quarts more oil.

 

Yes, the severe service as pointed out requires more frequent OCI's. This is basically if the engine and components aren't getting up to proper operating temperature (proper temperature helps keep weird things like carbon and moisture out of the oil and other places you don't want it to go...) etc... Personally, I did 3750 on my 2009 Legacy (severe schedule - normal schedule was 7500 intervals), but now they've made it 3000/6000, it's a lot simpler this way. I personally do 5000 mile OCI's on my Subaru Outback, which is a 4-cylinder EJ series that takes 5w30, but I run Mobil 1 High Mileage 5w20 and I change it every 6 months regardless of miles.

 

Remember, there's more to your oil than just the oil itself. You also need to think about the filter. If the filter can't filter effectively, all the little particulates (aka, nasties) are just circulating through the engine oil, reducing the effectiveness of the oil to do it's job - lubricate and cool.

 

So, while I sympathize with the cost of the service, you can always a-la-carte some items. I did that all the time before I started doing my own maintenance.

 

I have no idea what year your car is, just that you have the 3.6 engine.

 

I believe the 30k includes:

Oil change and oil filter, which you noted

Brake Fluid change, which you noted,

Front and Rear Differential drain & fill

Tire rotation

Engine air filter

Cabin air filter

 

That's really it. Remember, shops bill probably close to $125-150 per hour of labor.

 

The diffs are pretty important. I could argue that once you do the initial 30k rear differential drain and fill you could probably skip the next one and do it again at 90k because all the factory machining nasties are out of it... but I would want to probably hit the front differential again at 60k, maybe doing an oil analysis of it to see how it compares to the 30k one and then plan accordingly.

 

The air filters are super easy. You can get both OEM parts online or from your local parts department for somewhere between $30-40.

 

Rotation I would measure my tread depth before I proceeded.

 

An ounce of prevention is worth a pound of cure.

I believe the 30k includes:

...

Front and Rear Differential drain & fill

...

Cabin air filter

 

No. Please refer to the schedule in the Warranty & Maintenance Guide!

 

http://legacygt.com/forums/attachment.php?attachmentid=226470&d=1457854507

I believe the 30k includes:

Oil change and oil filter, which you noted

Brake Fluid change, which you noted,

Front and Rear Differential drain & fill

Tire rotation

Engine air filter

Cabin air filter

Thanks! Nope, no diff. change required on my 2016 at 30K miles. (Actually, no scheduled diff. oil change at all.) Just the filters, the oil and the brake fluid.

Thanks! Nope, no diff. change required on my 2016 at 30K miles. (Actually, no scheduled diff. oil change at all.) Just the filters, the oil and the brake fluid.

 

No! Read the schedule in the $#*(&^%$#! Warranty & Maintenance Guide!

 

http://legacygt.com/forums/attachment.php?attachmentid=226470&d=1457854507

 

I run quasi- severe schedule. Maintenance book specify 30k interval for diffs.

 

Cabin and engine I do yearly which happens to be a 10k interval for me anyway. I believe it says 30k for engine filter and 10k/12 month interval for cabins on the link you specified. It’s listed as HVAC filter?

Thanks! Nope, no diff. change required on my 2016 at 30K miles. (Actually, no scheduled diff. oil change at all.) Just the filters, the oil and the brake fluid.

Just because it's not scheduled doesn't mean that it's not a good idea to change the diff fluid now and then.

 

As for oil change interval - it really doesn't matter if you run synthetic or ordinary oil because both are only able to absorb a certain level of impurities before they start to accumulate in bad places in the engine. You don't want coke to build up inside the oil channels or other places where it can result in premature damage.

I run quasi- severe schedule. Maintenance book specify 15k interval for diffs.

 

What maintenance book are you quoting from?

 

My maintenance Book says 50,000km and then 112,500Km

Sorry, that was a typo. I meant to say 30k, as was the topic of the thread.

 

"Tranmission/differential. Front/rear gear oil *3"

#3. under severe driving replace 30,000 miles

 

Actually, I dont think it is a typo. I'll try to attach a PDF of my warranty and maintenance booklet. It says that in severe driving, replace note 3 items in 15k miles...

2011_war_and_maint.pdf

3.6R and have been changing it every 6k miles with conventional oil. Which is every three to four months for me.

"Tranmission/differential. Front/rear gear oil *3"

#3. under severe driving replace 30,000 miles

 

How much trailer towing do you do? Because "Repeated Trailer Towing" (example g.) is the only "Severe Driving Condition" listed in the Warranty and Maintenance Guide as affecting differential oil change interval.

Personally, I would change the differential fluids at 30k miles, it very likely has metal in it from break in. One my 5th Gen the 1st 30k was like this, the second 30k miles change the fluid looked clean and was probably overkill. The factory service schedule has one inspecting the fluid but never requiring a change.

How much trailer towing do you do? Because "Repeated Trailer Towing" (example g.) is the only "Severe Driving Condition" listed in the Warranty and Maintenance Guide as affecting differential oil change interval.

 

Good point. Upon further review I was confusing “item” 3 with “note” 3 in terms of reference. I guess it’s better to let it run. But I think I will still plan on doing an initial at 30k for any break in stuff to come out, and then probably 60k intervals thereafter. Maybe even 90.

I agree it's not the easiest presentation to follow.

 

Changing your differential oil every 30,000 miles (or 15,000 miles) probably won't hurt anything but your wallet, but it's far more often than Subaru recommends.

Personally, I would change the differential fluids at 30k miles, it very likely has metal in it from break in. One my 5th Gen the 1st 30k was like this, the second 30k miles change the fluid looked clean and was probably overkill. The factory service schedule has one inspecting the fluid but never requiring a change.

 

Are you sure that is correct? If it is then it must be different in the States, because in the Australian manual it says that the fluid is due for replacement at 50,000km and 112,500km ..... I find it odd that Subaru would allow one country to run forever without changing the fluid, and in another country mandate a change every 50,000 km (approx 30,000 miles)

Are you sure that is correct? If it is then it must be different in the States, because in the Australian manual it says that the fluid is due for replacement at 50,000km and 112,500km ..... I find it odd that Subaru would allow one country to run forever without changing the fluid, and in another country mandate a change every 50,000 km (approx 30,000 miles)

 

Not surprised that countries are different.

 

Canada spec requires CVT fluid drain and fill st I believe 100k kilometers now, which is about 60k miles. US only requires it if towing. Haven’t checked other countries yet, but do know that the “inspection” of US based CVT maintenance means only to inspect for leaks per the July-ish TechTips newsletter. Additional work to visibly inspect the CVTF per the service manual is only justified on the CVT if there is a visible leak, or you’re in there doing a drain and fill for a towing severe service schedule or if you’re replacing another component like a bad torque converter.

Not surprised that countries are different..

 

I hear what you are saying, but I must admit that I am totally surprised that important maintenance procedures could vary so much from country to country.

I can understand for example, local conditions, or the towing you mentioned could affect the maintenance time frames, but I find it very strange that procedures could vary so much between countries. Surely the original Subaru designers in Japan must have maintenance parameters that would be generally applicable in every market that their vehicles are sold in. I find it equally strange that a local manufacturer could unilaterally decide if they wanted to follow original maintenance specs or just run their own race.

Different countries with different climate and usage patterns for the vehicles. In Europe at least the Outback is approved for trailers up to 2000kg (give or take a bit, varies somewhat on model).

 

Customer protection laws also plays a role.

Just because it's not scheduled doesn't mean that it's not a good idea to change the diff fluid now and then.

 

As for oil change interval - it really doesn't matter if you run synthetic or ordinary oil because both are only able to absorb a certain level of impurities before they start to accumulate in bad places in the engine. You don't want coke to build up inside the oil channels or other places where it can result in premature damage.

Yeah, I recognize that lots of things people do outside of scheduled maintenance are considered to be a "good idea", but I am interested only in "by the book" required maintenance. That's why I mentioned that above.

Different countries with different climate and usage patterns for the vehicles. In Europe at least the Outback is approved for trailers up to 2000kg (give or take a bit, varies somewhat on model).

Customer protection laws also plays a role.

 

You raise the point of customer protection laws ..... that's probably a relevant issue that I hadn't thought of, and that I could see might enter into the equation ...... but I'm not convinced about climate so much. Big countries like USA and Australia have a vast difference in climate depending on what state you are in ..... so I can't really see that being a factor in a maintenance schedule. Imagine buying a car in Maine (where I am assuming it's pretty chilly at times) and taking a job transfer to Florida and driving your Subaru down there. ..... would they have a different owners manual??? And if your car was out of warranty and you never went to a dealer but only relied on the manual that you got with your car (in Maine), how would you know if the new climate affected your vehicle's maintenance??

 

It's not a big deal and I'm not intending losing sleep over it, but I just find these different maintenance requirements a bit strange

The post at the bottom is nearly 12 years old, but I wonder if the information he mentions has anything to do with it.

 

To make a long story short, I wonder if the gear oil, or whatever diff oil they use is different in Australia and other places that call for a 50k km and 112.5k km maintenance interval. Maybe it's largely a group II or II+ conventional basestock which drives subaru to recommend more frequent replacement. I understand synthetic gear oil must be available there too, but I wonder if subaru dealerships in other parts of the world are using a conventional gear oil.

 

Years ago there were discussions on bobistheoilguy about how can the US call for 5w-20 oil for a car, but europe and other places called for much thicker oil for that same car. Some said CAFE, but the person in the link below essentialy said it could be because the synthetic basestocks needed to produce a good 5w-20 simply weren't available in other parts of the world, at least not in large enough amounts.

 

https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/674209/Re:_5W-20_people_-_explain_thi#Post674209

Honda had 7200 mile oil change intervals back in the late 80's... with dino oil...

 

the problem that you are going to run into id the additives package breaks down before the oil does...