Can't intelligently speak to the Rotella, but I was using the Delo 5w40 in my Detroit 60 and got some unexplained shearing going on. Viscosity was dropping to a 30 wt in normal OEM intervals. Since then, I went over to the Schaeffer 9000 and do not get the shearing and am able to almost double the OEM recommended drain intervals.
Have no explanation why the Delo was shearing. One of life's little mysteries. But I get the Schaeffer delivered to my door, complete with free oil sample kits and analysis, for the same price I was getting the Delo at wally world.
Hey there, VA, what do ya say? How many vets did you kill today?