Looks like Amsoil 5w-40 now meets VW 505.01. Yet now it only meets API CF when it used to meet API CI-4. What's up with that? Why is it an oil that's made to meet 505.01 can't also meet CI-4?
Because it is now an API SM type formulation. It probably uses a reduced level of additives now; I'm guessing that they switched to an API SM type formulation to satisfy the stiffer SAPS limits required by the newer ACEA and BMW specs.
The other two 505.01 approved oils available in the USA also only meet API CF. Those two oils are Castrol 505.01 & Motul 505.01
It must not be possible at this time to blend an oil that will meet VW 505.01 & API CI-4.
I'm suspecting that it has something to do with meeting the latest ACEA C3-04 and BMW LL-04 specs...I think those require a very low SAPS that isn't attainable with a CI-4 additive package. Just a guess...
You guys are a rough crowd. I mean that in a good way.
Seriously - I think for a company that must seriously guard it's formulas - Amsoil is pretty darn transparent. Name names of other companies that are abused by you jokers so much.