Originally Posted By: chrisri
Originally Posted By: Shannow
Originally Posted By: fdcg27
Originally Posted By: chrisri
That doesn't change the fact that every engine should wear less with Euro 40 grade than with 20 grade SN stuff...
What would be real life difference is another matter.
You just spitballin', or you have something to back this up?
Adding some spit to the ball...
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1064688&page=1
and a google books link
Not supportive of the blanket statement, but when viscosity can't keep the parts apart, then additives come into play, and bearing materials become sacrificial (over the long term, no pile of failed engines today).
Great post Shannow , dynamic viscosity and stable,
shear resistant base oils are IMO most important part that protects engine from wear. Oils designed bh Euro specs have to retain its starting HTHS even after 20k of use. This was main reason ACEA organization was founded years back. Old formulas would share after 20k KM OCI that was common over here in early 90s before ACEA came to the scene.
It isn't the base oils that shear, but rather the VII's. Better base oils allow the use of less VII's and subsequently result in a more shear stable product (over simplifying a bit of course).