Subaru Legacy Forums

Subaru Legacy Forums (http://legacygt.com/forums/index.php)
-   Second Generation Legacy (1994 - 1998) (http://legacygt.com/forums/forumdisplay.php?f=95)
-   -   syntetic to standard (http://legacygt.com/forums/showthread.php?t=162516)

crash98 05-21-2011 11:48 AM

syntetic to standard
 
ok so i work at a shop and have herd that you shouldnt switch between synthetic and standard oil but never got a good answer why. also i was wondering if its worth it to put synthetic manual trans fluid in

broknindarkagain 05-21-2011 12:09 PM

That has some truth behind it, but for the most part its not true.

Most commercially available "synthetic" oil is based off of conventional (regular) oil. Its broken down and basically "rebuilt" in a lab. Its safe to mix this type of synthetic with conventional, or switch between the two as much as you want.

The other kind of synthetic oil is REAL synthetic oil. There isn't much around, and what is around is VERY expensive. Amsoil is the only company that makes real synthetic that I'm aware of. This kind of synthetic isn't suppose to be mixed with conventional, or even conventional based synthetics. This type of oil is built in a lab from scratch. Its 100% man made, where as your normal synthetics are just modified conventional oils.

Now the reason behind the thoughts of not switching between the two is because when you drain the oil, there is still some leftover inside the engine. The only way to get ALL of the oil out is to do a complete flush.

With that being said, if you switch from Pennzoil, Castrol, Mobile, Quakerstate, etc synthetics to convention (or the other way around), you will be just fine.

A lot of automotive sales people use the line "Well you ran synthetic last time, so you have to use it every time now." to get more sales. They rope you in the first time, and make you feel like you're trapped into using it afterwards

Gire 05-21-2011 12:25 PM

I decided to go synthetic after my first year of ownership.

Then after 3 years of oil changes at the dealer as needed, their oil changer made a mistake and switched me back to regular. I didn't complain too much as they were covering a transmission problem at the same time that I thought I'd have to pay for.

I've been back to regular oil for the last couple years. No worries.

I just don't think I will switch back to synthetic even though I love the loner intervals between changes.

Baddog 05-21-2011 12:29 PM

I just feel as if I am getting better protection from using a Synthetic. A good brand at that. My engine feels smoother with RP. I was running Shell and Mobil-1 before.

I also USE my car. I don't just daily drive it. I abuse it. So I make sure I spend that little extra in oils for added protection.

thefultonhow 05-21-2011 12:51 PM

There is a lot of misinformation in this thread, and it's not even that long yet.

First of all, to the OP, the reason people say not to use synthetic after using conventional oil is that, theoretically speaking, the additive pack in the synthetic will dissolve the deposits of dino oil around seals. With the deposits gone, there is more room around the seals for the new oil to leak out. I'm not sure I buy this argument, though. Plenty of people switch without having any problems, and if you have oil leaks, you should replace the seals, not pray that the deposits keeping the leaks manageable stay there.

Quote:

Originally Posted by broknindarkagain (Post 3399329)
The other kind of synthetic oil is REAL synthetic oil. There isn't much around, and what is around is VERY expensive. Amsoil is the only company that makes real synthetic that I'm aware of.

Shell Rotella T6, German Castrol Syntec, and I beleive Pennzoil Platinum are also true synthetics (i.e. PAO base stocks rather than refined dino base).

Quote:

Originally Posted by broknindarkagain (Post 3399329)
This kind of synthetic isn't suppose to be mixed with conventional, or even conventional based synthetics. This type of oil is built in a lab from scratch. Its 100% man made, where as your normal synthetics are just modified conventional oils.

Where did you hear that? They are all oil. The advantage of synthetic is that it breaks down more slowly and (usually) has a better additive pack. Normally, you don't have to change true synthetics as often as dino oil. Some are reporting 7500-10000 mi. between changes on EJ255s (notoriously hard on oil) with Rotella T6, and the UOAs say the oils even have a bit more life in them. But, if you were to mix Rotella T6 with Quaker State (widely considered to be crappy oil), as long as you keep an appropriately short OCI, there is no way you can damage your engine.

Quote:

Originally Posted by Baddog (Post 3399337)
I just feel as if I am getting better protection from using a Synthetic. A good brand at that. My engine feels smoother with RP. I was running Shell and Mobil-1 before.

Too bad Royal Purple does not have any oil industry certifications. If you want to talk about selling "snake oil," Royal Purple does it. Maybe they are good, but they have no proof.

broknindarkagain 05-21-2011 01:18 PM

Pennzoil Platinum is dino oil

thefultonhow 05-21-2011 01:30 PM

After doing some research, you are partially correct. It is synthesized from a blend of Group III and Group IV base stocks. It is not fully Group IV. However, it is not "dino oil" in the traditional sense. It still qualifies as a "full synthetic" and is up there with full-Group-IV oils in terms of the UOAs.

broknindarkagain 05-21-2011 01:40 PM

I've heard (don't have proof though) that a lot of the "synthetic" oils on the market are just conventional oil with additives in them. Wouldn't surprise me if this is the case.

thefultonhow 05-21-2011 02:03 PM

Quote:

Originally Posted by broknindarkagain (Post 3399376)
I've heard (don't have proof though) that a lot of the "synthetic" oils on the market are just conventional oil with additives in them. Wouldn't surprise me if this is the case.

Most of them are synthesized from a combination of Group III and Group IV base stocks, like PP is. As a thread I read on Bob Is the Oil Guy said, though, the base stock matters less than the UOAs. If an oil gets good UOAs, who cares what the base stock is?

Baddog 05-21-2011 04:10 PM

The RP did cure a halt in the engine. Not sure what it was but around 4k RPM's it felt like the engine fell flat on its face. I put in RP and it even feels smoother in the low end and doesn't fall flat on its face anymore.

I will give AMSoil a try next time. I haven't read many problems with RP and it really has helped my engine out. So I will stand by it for that fact.

thefultonhow 05-21-2011 06:40 PM

Quote:

Originally Posted by Baddog (Post 3399497)
The RP did cure a halt in the engine. Not sure what it was but around 4k RPM's it felt like the engine fell flat on its face. I put in RP and it even feels smoother in the low end and doesn't fall flat on its face anymore.

I'm not convinced that's not just a coincidence. On my brother's 2001 Forester, a hesitation at 3000-4000ish was caused by a bad front O2 sensor. It's possible your O2 sensor was temporarily acting up and stopped at around the same time as you put in new oil. Unless you keep oil in way past when you should have changed it, or you use too heavy of a weight, there's no way brand of oil would affect a hesitation problem.

Baddog 05-21-2011 08:23 PM

Alright. Well this is gonna turn into an awesome debate. I will try amsoil next. So far my engine feels smoother is all I am saying.

I ran a 5-40 and ran it for about 5k miles. Rotella T6.

broknindarkagain 05-21-2011 10:16 PM

The original poster only has 1 post. Maybe someone just registered to strike up the never ending oil debate lol

cbt299 08-15-2011 10:28 AM

Quote:

Originally Posted by Baddog (Post 3399497)
The RP did cure a halt in the engine. Not sure what it was but around 4k RPM's it felt like the engine fell flat on its face. I put in RP and it even feels smoother in the low end and doesn't fall flat on its face anymore.

I will give AMSoil a try next time. I haven't read many problems with RP and it really has helped my engine out. So I will stand by it for that fact.

how often do you change with RP?

Baddog 08-15-2011 04:32 PM

Usually around 4-5k miles depending how hard I drive it.


All times are GMT -6. The time now is 06:48 AM.


LegacyGT.com