[Dj Hurricane]

Today I got my first service at Subaru...

I went to AutoZone and bought Royal Purple 5w30.

So when I show up to get the Oil change the guy tells me "you cant Put full synthetic in a subaru"....

So I tell him, this is not my first subaru, and ask him why would that be...

He tells me, he dosn't know, but Subaru told them that...
and that it Could void the factory warranty....

So, I tell him, "Under the warranty ACT, They can not do that" and would have to show some reason that Synth Oil caused said" malfunction.

And Insisted he use the Royal Purple.

Then I called SOA, to see what was up//

The SOA rep told me:

"Subaru's Stance is not to void warranty for Synth oil, as long as regular timely intervals were maintained, and same weight oil was used as recomended."

[pisymbol]

For some odd reason (since I use Mobile 1 5w30 religiously) I was told that full synthetic in these cars is not really optimal. I have no idea why - this maybe BS.

[GilMikalian]

I may be oversimplifying things but why try to fix something that ain't broke. Dino oil has been working just fine LONG before synth came around. If you intend on changing the oil every 3 or 4K miles or so, why bother with synth...especially since there is a chance that there is either no advantage, or slight disadvantage, to doing so based on several experienced Subie techs I've spoken with? I mean, pay more for higher risk, with little to no benefit, this seems like a no-brainer. What am I missing and why the insistence of using synth. And I'm not singling out the OP, I've heard MANY people, both here and other boards who swear by synth. Why not spend the $$ on more frequent oil changes with dino oil, although anything less than 3K seems to be overkill.

[Blackfang]

Your service advisor was a toolbag. The only thing I warn my customers about when using full synthetic is becareful of M15w30 because it has lead to oil consumption and do not go beyond 3750 for oil changes on a turbo engine with synthetic

[jermdeez]

Yep. I believe the dino is good for subies for about the first 8k or so to fully break them in, then switch to synth. Synth lubricates better than dino so there is an advantage.

[mondojava]

It's my understanding that the main advantage to synth is that it's viscosity breaks down much more slowly. So, while dino and synth may start out with the same lubrication qualities, the dino denegrates much more quickly. How quickly is the key. I have read where dino starts deteriorating right away. If someone can show me that the lubrication qualities are the same for both at 3750 miles, then I would buy dino.

[Brand]

Originally Posted by mondojava

It's my understanding that the main advantage to synth is that it's viscosity breaks down much more slowly. So, while dino and synth may start out with the same lubrication qualities, the dino denegrates much more quickly. How quickly is the key. I have read where dino starts deteriorating right away. If someone can show me that the lubrication qualities are the same for both at 3750 miles, then I would buy dino.

I don't believe that is correct; they don't start out with the same lubrication qualities. Synthetic oil, being synthesized, has molecules with a consistent size and weight. This allows the oil to flow more easily and results in more consistent viscosity across a range of temperatures. As a result, you get better engine starting at cold temps and fewer engine deposits. Any other benefits (such as it lasting longer) are simply a result of the consistent molecules. It has also been shown that a car running synthetic will put down more HP on a dyno due to the reduced friction.

[Julio08OBP Sti]

its all about temperature vs. viscosity. im in the northeast, and the low temp/low cPs character of synthetic helps greatly with start up wear.
ive done some gc/ms analysis of the the factory dino that came in my car (@1K mi) as well as the syn i put in after 1000 miles (I now have 2000 miles on my car, the syn sample). i took a peak at my coolant, wondering if i could id a few of the hydrocarbon players from the different oils.
ill post the data later, as my gf has me on the hook for my hold 'em escapades this weekend. i can quantitate all this shortly. (i know, its just 1x)
for summary, syn is cleaner, and provides better start up protection. it produced a more consistent mw hc; by a lot. the factory syn had much more small mw chains than i expected. i cannont comment on longevitiy and breakdown.
blow by from either seems equal at this point. (i havent associated the low mw peaks)

[mofoSTI]

I used only mobile one synthetic in my 04 STI. Now with my new 08 STI I plan on only running gtx 10-40