Just a tip .
Energy conserving oils come by way of lower viscosity oil . 5w-20 , 5w-30 and most 10w-30's and are built to shear . The automotive 10w-40's loose out soley on getting that EC rating from being too thick/viscous to pass the Sequence Tests .
The very few 10w-40's that would pass the EC test have viscosity shear built into the formula as well, just as their 30 weight brothers in the line-up and seldom do these shelf oils have different additive packs . 10w-40 Castrol GTX looks to have the near same add pack as the 5w-30 as example . 20w-50 for that matter . Exxon 5w-30/Exxon 10w-40-20w-50 ect.
It's subject to change soon but most current registered JASO MA oils have right around 1200 ppm phosforus , 1300 parts per million zinc as anti-scuff/anti-wear additives . Others have from 2000 ppm to 3200 ppm .
Most if not all shelf product API SM GF-4 automobile mineral oils contain only 500-600 ppm of each ----- this includes the Exxon 10w-40 .
A little fuel dillution , some permanent polymeric shear and these shelf oils can be lowered to a 8 centistoke 20wt from a starting 13.2 cSt 40wt in matter of
?? 1000 miles , depending on much .
When I have a 20wt in my engine it is made of TMP , diester or blends of pentaerythritol and polyalphaolefins . These base oils have inherent film strength that mere mortal groups of base oils don't . Please don't point out a test thats on the internet. The oils I use were not included in that one and I often wonder why .
As valve train loads become lighter and lighter there's some big changes coming year 2010 for JASO rated bike specific oils . Thank goodness for Maxima and a handfull of other independents because these bikes will still have transmissions to protect .
