02 F250 / 7.3L / 4X4
Today I noticed after driving for about 2 hours on the freeway, I was getting grey smoke instead of black. But after getting into the town, it was back to black smoke. When I first saw the grey smoke I thought it was just cuz of the speed I was driving, so I slowed down to about 40, and at wot I still got grey smoke where normally it would be black. Would that long of driving cause grey smoke? No change in performance. Also, coolant and oil levels are good. Any ideas?