skip029, Lower wear scores are better, as thats our best source of info. Sure there is some variability, and fleet testing can help there. Yet, we go with what we have. Sure maybe the National Ad Division NAD can fault Castrol when they claim an 18 micron score on IVA when that was only on one engine test run, yet it would stand up in court if the documentation was produced to prove it once got that. .... One solution is to create a new certification that actually puts an oil through 3 years of use in a fleet of 10 vehicles, tearing down the engines and measuring wear performance and normalizing for miles.