Originally Posted By: CATERHAM
Originally Posted By: 05LGTLtd
T6, M1 0w40, GC, PU 5/10w30 are all proven fi Subaru oils.
That's quite a viscosity range, HTHSV 3.1cP (PU 5W-30) to 4.0cP (T6).
If the lighter oil works, with all the inherent advantages on start-up, etc not to mention being the spec'd grade, it doesn't make much sense to use anything else particularly for street use.
That is quite a range, yes. The 10w30 PU at 3.2 or 3.3 (icrrn) or the M1 and GC at 3.5ish are the middle of the pack. Depending on climate, if you want to run thin, then 5w30 PU has given some good feedback here and elsewhere. But if your moderately (me) or heavily modified, then going a little higher on the hths scale is possible. Also have to factor local temps, driving application, availability and cost.
My manual specs 10w40 and 20w50 as applicable for my engine. I've said it before but I'll say it again: at no time between 2002 and 2012 did subau make any significant tolerance changes in the ej construction. They did change their spec's and I think they did so because... A. They think that the average consumer is not responsible/capable enough to choose an oil from their chart in the manual. B. They did so for precieved legal/cafe reasons. If any one can find me a tsb where Subaru decided to change the oil grade recommendation retroactively or proof they changed the engines internally to tighter tolerance, I'll recant.
Just because an oil has the Honda turbo spec, don't automatically assume it won't shear down in asubaru in a 3750oci. I put more faith in the A3 spec and some of the tougher euro manufacture's specs that also meet A3 from VW, Porsche and MB.