All I use is synthetic in my truck, but that was after a complete overhaul of the engine. Synthetic has many benefits but if you start using it in a worn engine you may end up with more problems than benefits. Like Bluesman17 said, it does find leaks easily and leaks fast. I had heard before that it doesn't take any special procedures to start using synthetic, but once you go synthetic you can't go back. I couldn't figure out why so I called a Royal Purple rep to inquire about it. I was told that many synthetic oils have their own propreitary blend of additives in the oil, most of these additives will bond to the metal in your engine and if you decide to go back to using regular oil this bonded additive will start to wear irregularly. But like I said, I run synthetic in mine and have no problems at all, so I really believe it just depends on your engine.