I have a 91 6.2 and it is running great on WVO. I had a 87 6.2 in a Suburban just burning diesel. Both engines got/are getting 20mpg on diesel. I am not sure what my mileage is on WVO as I haven't had it long. Personal experience with the 87, I cracked a piston but got rid of the truck because of the transmition. I would not recommend doing this unless you are somewhat mechanically inclined or willing to learn. It is dirty and somewhat strenuous especially at first when you are learning. I feel it is worth it as we own an RV and like to do road trips. The hardest part is finding the truck although a GOOD source of oil is not easy to find. Look in the classified section of the sites that sell the conversions for the truck.