I haven't done any used oil analysis yet on my 1996 Jeep Grand Cherokee with the 5.2L V8. I've got 98,600 miles on her so far running Chevron High Mileage (first oil change with this stuff). Previous oil changes, Chevron supreme 10w-30 was uses. Lately I've been thinking about switching to M1 Truck/SUV 5w-40 just for maximum protection since I drive the hel* out of my Jeep. I know it's hard to tell someone that a particular oil will be fine without a used oil analysis, but do you guys think that this oil should be ok or will it be a little to thin to begin with? Anybody run this stuff in higher mileage vehicles or in dodge magnum engines? I did an Auto-RX treatment about 9,000 miles ago.