finally found the 5w-20 TSB...

[sbergman27]

Originally Posted by TheSilkySmooth

What else?

Yes, all multivis oils are thicker at cold temps than at operating temperature. I mentioned the fact because it is widely misunderstood, and people who do that tend to recommend 10wX oils or straight weights.

I would not expect to be able to measure the difference between AFE 0w30 and a 5w30 without a lot of very systematic testing. I seriously doubt that your 5 mpg difference has anything at all to do with the oil.

Engines don't see EP. They see sliding friction under very high shear conditions. Lot's and lots of it. What, exactly, do you think that extra EP additives are buying you? And what are the down sides, I wonder?

You are, of course, free to second guess the engineers as much as you please. Especially if you are out of warranty. But you do it at your own peril. And I'd be particularly nervous going further and telling *other* people to use it.

That said, if you are looking for an impressive oil that meets a range of European (and particularly German) high performance standards which almost no other does, and has an HTHS of 3.7... look to Mobil 1 0w40. If I were going to stray from the spec'd 5w30, that's what I would use.

http://tinyurl.com/39b6cg

BTW, why don't you care about your (and other people's) catalytic converter?

-Steve