I have a friend that has a 08 that he bought used. The problem is that his fuel gauge is reading about 1/4 tank lower than it actually is. We tested it to my duramax the last time we went camping. The dealer that he bought the truck from told him it was because the previous owner never let the tank get below 1/4 of a tank. They told him if he would just keep running it down then eventually it would reset. Well he has been doing this for awhile and it is still reading lower than it actually is. Has anyone got any suggestions on something he can try. Or have you ever heard of this problem. I know the older duramax trucks have had problems with the sending unit, but not sure about the newer trucks. Thanks for your help.