Well my old POS F150 is finally shot I think. Needs a rebuilt motor and that would be worth more then the truck. My friend at work has been bragging up his newer Silverado and the mileage he gets. I read some horror stories about AFM and VVT at first when they were comming out with and the trucks not firing on certain cylinders and burning lots of oil. Should I stay away from buying a used Silverado with little to no warranty that has AFM and VVT? or has the problem's been fixed and I have nothing to worry about? Any years and sub models I should stay away from?