Originally posted by beepbeep
Mobil 1 doesn't use PAO as a base for it's synthetic oil in USA, as far as I know. I guess that doesn't make it a synthetic oil anymore.
Anyway, todays oils are much better than oils that were around when theese cars were sold anyway.
I have good expirience with Shell Helix.
Shell Helix is the same as Shell rotella T synthetic in the states. And yes mobil bit the bullet like shell did and use group III basestock for there synthetics which is a highly refined petrol oil. They also use group IV (pao) and V(ester) in small amounts as part of the additive mixture to get there desired results from the oil (at a lower cost). For aircooled motors, they generally see piston temps similar diesels which is why in my opinion rotella, delo, and delvac should be good oils for the cars. If you look at the certifications met on the back, CJ (C standing for commercial not combustion like some think) is the lastest standard for commercial diesel and gas engines, which prefer long drain intervals and higher temp viscosity stability. SM (S standing for service engine, not spark) is the latest standard for normal passenger vehicles however it is also an energy conserving standard and also has little zinc to help keep from destroying cat converters of modern cars.
Look around the forums on www.bobistheoilguy.com
this is where i read a lot of that information. Of course if you want to run a genuine PAO class synthetic oil, then these days your limited to online oils such as ams, redline, motul, ect. For the record, there's nothing wrong with group III base oils, however, while they are close in performance to a PAO these days, there viscosity index still isn't as good which is why that 5W-40 you mentioned thinned out to a 5w-30. A 15w40 oil only needs enough additives to become 1.5 times higher in viscosity at operating temperature, where as that 5-40 needs enough to go 8 times so when those additives break down, guess what happens to that 40 weight oil at temperature.......... it goes down.
Oh by the way, if you need to know why i picked those three oils mentioned above, go to that bobistheoilguy website and check the motorcylce section and see what the aircooled bikes and atvs run. That stuff even works through there gearbox (for the ones that share motor oil with the trans) and that will generally destroy most automotive oils but these seem to hold up very well.