the suberban ones are indesructable. guy visited my work the other day and when i asked him how many miles he said 320 K on the origonal motor. He said he was the origonal motor and has used z max since he bought it. Lol im now a believer in the stuff. And fyi he really did. i read the code on his truck when the motor light came on and it was having a misfire in one of the cylinders due to a coil but.. yah. shows what taking care of your shit does for ya.