[Hblick48]

We have 2005 F250 6.0 diesel. Purchased it from original owner when we got Montana from him, truck had 110,000 miles on it at that time. He kept a log of all work done on truck since new. He changed dino oil and filter every 3,000 miles. He changed to Rotella T6 full synthetic at around 90,000 miles and extended oil change interval to 5,000 miles.

Truck now has 145,000 miles on it. About 15,000 miles ago, I sent oil to Blackstone for analysis. They said engine is in great shape, and I could extend change interval to 6,000 miles.