"A few years back, I had my 2001 Ford F-350 diesel engine removed to replace a leaking oil pan. While out my mechanics told me my engine was extremely clean for one with 90,000 miles on it. I can only conclude it is because I use the Lucas oil treatment in every oil change since the truck was brand new. They said they would probably have to agree with me. They took pictures for me to look at after they put the engine back together, and they were right, the engine looked brand new. Literally nothing on anything, it looked as if it was never used. Good product, Thanks." -Thomas Rose