You know, I was reading your post, and was thinkng, "wow this dude really knows his stuff." But then I read your signature, and thought, "oh crap!"SD_GR said:Not changing at 3K mi is not a matter of "missing the mark," as there simply is no mark. None. To maintain your warranty in case of a motor failure you ought to follow Subie's interval and grade rec's, but other than that, the only way to know if it's time to change oil is to do oil analysis. The lab will let you know how the oil is holding up, and whether you've got elevated insolubles in there etc.. It's a matter of sampling 100 ml or so from the middle of a slow drain, sending it in with a check, and getting the news in the mail to find out, but I concede it's a huge hassle at times and I presonally don't like doing this. Cost is about as much as a full synth oil change.
Dark oil isn't good or bad; for every person that says "the oil is black, it must need changing" there's another that - like me - *likes* dark oil, b/c I believe that if it's dark, it's got nasties in solution, which is one reason I put it in the motor in the first place. I too use M1 10W-30, since M1 doesn't come in a 10W-40 that I'd prefer and the fantastic M1 0W-40 is not a permissible range according to our manuals in the US. M1 is on the thin side of the xW-30 range, and I don't know how well it'll hold up with typical use in my climate (southern CA USA), but I'll just have to find out.
I won't accept intervals shorter than 4K at this point, as there's no reason for a road car to use synth oil at a faster pace in the 21st century IMO. I plan to run this first lot of M1 for 3750 like the "good book" says, then increase the drain interval as I get an idea of what's going on. The first change isn't going to be meaningful data-wise, since the motor is still newer and the synth is diluted with some remnants of dealer dino juice. As I go a couple more drains, that'll no longer be an issue. We'll see...
None at all. Actually, there's compelling reasons to *use* M1 0W-40. It is their flagship gasoline engine oil in the USA. It meets ACEA A3-02 and Merc's MB229.3; both are very stringent specs (whereas API SL is laughable in comparison). I can only think of a very select group of oils commonly available in the USA that meet these specs and are therefore engineered to such high standards (and M1 15W-50 is one of them).wrxdude said:Is there any reason why we shouldn't use a 0W-40 synthetic oil in our wrx's? ... Thanks.