2kool4skool
Senior Member
Since we've had 2K4S I've run 15-40 diesel oil. Generic, from wherever. In January I changed to Rotella t4. We drove our usual route to and from Skooliepalooza. Going home takes us up I17 with 6% uphill sections and in January we were held up a few times (not unusual) by big rigs so our uphill speed was unremarkable and about what we normally do. Lowest speed=23 mph. We drove up the same hwy on Thursday and there were no slow trucks so we able to climb the grade at 35 mph as our lowest speed! I'm sticking with Rotella from now on.