Originally Posted By: CATERHAM
But my point is, there is no shortage of 10W-30 dino's that exhibit some oil shear and some high quality 5W-30 and even 0W-30's that don't shear at all.
But the real message is that one doesn't have to settle for a low VI 10W-XX oil as today's crop of 5W-30 oils have very acceptable shear rates. If you want a heavier 30wt oil choose a higher HTHSV 5W-30 oil. Reverting to a 10W-30 grade is very much old school thinking.
I believe dino 5W30 today is better than 10 or so years ago, also it is better than today 10W30 in most engines.
But the problem I'm facing is my S2000 spec'd only 10W30 for warmer climate (and 5W40 for colder area), since the car is rev'ed to 7-8k daily(after 10-15 minutes drive) and fairly high RPM on highway (4k-5k), I'm reluctant to use dino 5W30.
But, if I use syn oil in it then I may mix 3 quarts M1 AFE 0W20 with 2 quarts 0W40 to get a thin 0W30.