I am confused, The dealer is constantly trying to get me to change my differential fluid, Transmision fluid , power sterring fluid etc... My mechanic dosn't seem to think it needs to be done. He has said that once you start its a never ending expence. My dad as well as others have run well over 100,000 miles without doing it. I do some light towing on ocasion but most is city driving. Who do I believe? This expence at the dealer is alot. I also have two years left on my extended warranty. Help me decide please.