http://www.smrt.us/FXT/VOA/VOA%20-%20Castrol%20GTX%2010w-40%20API%20SM%20%26%20GL-F%204.gif

This was the only 10w-40 dino oil that I could locate locally that meet Subaru's warrenty needs (API SL & GF-3). I'll have a UOA on this oil in aproximatly 2.5 months.

...actually reading in the 40 weight range. :cool:

I wonder how this would compare to M1 0W40. The GTX might be more shear stable. I'm running German Castrol now but the fact that it doesn't meet warranty requirements has me a little paranoid.

No one would be able to tell since it's so thick, unless a dealer asks for proof of purchase. Maybe I'll look into a 10W30 blend.

-Dennis

Well you can also compare the price difference. A full blown synthetic like M1 0w40 runs close to $5 a qt. I think i paid just a hair over $5 for 5 quarts for the dino GTX. :lol:

How long are you planning on running it?

-Dennis

I'll draw a sample at 3 months or change it at 3k whichever comes first. Chances are very high that 3 months will roll by first. I just got in the mail my reminder for my 7.5k service. I have just over 2k on the car. :lol: I just don't put enough miles on the car to justify the extra cost of the synthetics.

I just don't put enough miles on the car to justify the extra cost of the synthetics.
Although the turbo would probably be happier with the extra additives in synthetic. No biggie if you're not going past 3.7-4k on your OCI's. Looking forward to your UOA's and get out and drive!!

-Dennis

Although the turbo would probably be happier with the extra additives in synthetic. No biggie if you're not going past 3.7-4k on your OCI's. Looking forward to your UOA's and get out and drive!!
-Dennis

a) synthetics do not necessarily have extra additives
b) extra additives mean extra sulfated ash
c) turbos do not like sulfated ash

On top of it, synthetic base oils have poor additive solubility.

Castrol GTX is excellent oil for Subaru engines. In my experience, Subaru engines run smoother and quieter with GTX versus Mobil 1, for example. Also, according to oil analysis that I have done on my Imprezas, GTX leads to lower wear compared to Mobil 1.

a) synthetics do not necessarily have extra additives
b) extra additives mean extra sulfated ash
c) turbos do not like sulfated ash

True, not necessarily. But looking at M1 0W40 VOA's it does have more additives.

Do you know where to find the sulfated ash of GTX? I didn't see the conventional oil sheets on Castrol's web site.

That's the great thing about UOA's. We'll be able to see how the oil is doing in his engine. :banana:

-Dennis

Yeah last time i checked the data sheets I found for the Castrol GTX did not seem to correspond to their new SM/GF-4 formulations. I know people often snag them from Walmartstores.com but I've never been able to find where they store their material data sheets on that site.