a1 vs a3 - how important is it really?

[JHZR2]

I was thinking... a lot of performance cars prefer mobil 1... mitsu lancer turbo (19 psi I believe!), porsche turbos, subaru wrx turbos, MB AMG supercharged cars... as well as a bunch of na performance cars. and they typically use M1 10w-30, an A1 oil. Now, I think its safe to assume that under high temp/high shear, high stress conditions, and A1 oil will not hold up as well. yet, they reccomend A1 mobil1. Why is this???? -any damage that would occur wouldnt be realized until the car is way out of warranty -the engineers at these companies are idiots or didnt think of it -it doesnt really matter, tolerances could accept a 20wt oil just fine, so long as its synthetic Any ideas? I just have had such a strong feeling of necessity for A3 oils (like in my brother's 3000 GT twin turbo), but maybe its not all that necessary... Any comments? JMH

 

[Motorbike]

Mobil Supersyn 5 & 10w-30 are A5 rated oils.....not A1

 

[Eiron]

Porsche turbos & Saab turbos recommend Mobil 1 0W-40, which is A3.

 

[Motorbike]

No fear of 9.5 to 11.9 cSt A5 oils from me as they can go the distance quite well . A5 is equally as tough , just in a lighter oil . Most high end Euro motors need at least a solid 12 cSt oil though . ACEA Sequences

 

[JHZR2]

In reading and searching the archives, Ive noted that there has apparently been discussion of how high HT/HS such as in an A3 oil is not necessarily the best thing. However, I didnt see why. The only info I pulled was that the higher the HT/HS, the lower the fuel econony compared to other equal weight oils with lower HT/HS ratings. But what about vaporization or protection, of a synthetic, in a low-revving american engine? Thanks, JMH