A friend swears by Duralube. He would replace one quart of oil with it at each change. I tried it in my F-150. By coincidence the motor blew soon after. The head gasket was suspect before the change. His wife's Elantra seized at 101,000 miles, just out of warranty. With the regular oil changes, it should have lasted much longer. When they needed to sell their Grand National, all I could think was the turbo saw Duralube.