Just thought Id share with you guys that this truck came into the shop I work at today and this is the 4.2 v6 model. It had 355k on it and the guy said the motor had not been touched and the only thing done to it was 2 clutches and slave cylinders. He also said that he changes his oil every 15k!!!!!! The oil we use is Mobil 10w30 bulk. I doubt he brings it to us everytime but going that many miles on different dino oils seems kind of far fetched. He also said that he changes it every 15k because someone told him that if you change it to often it will cause leaks due to sludge buildup. I said that if he had changed it often from the begining that he wouldnt have to worry about that. According to him this is all stop and go driving and is a work truck. What do you guys think?