Topping off tank - when to stop?

mielock wrote:
I was topping off my truck with diesel recently knowing I was right on the edge of a tankful of fuel taking me my entire drive, so for the first time I squeezed all the fuel I could in the tank and was shocked that I was able to add an additional 3-4 gallons. I just let the foam die down and added more fuel multiple times and the tank kept accepting more. That equates up to an extra 50 miles of towing, which is substantial. Has anyone else not accepted the first time the fuel handle automatically pops off, and kept adding more? My owner’s manual warned that this might cause spilling, which wasn’t a problem, so if that is the only problem I don’t see why not to do this each time.

There is an expansion area in the top of the tank that gets filled when you do this. There is actually a tank vent "mod" you can do by dropping the tank and adding a vent hose in this area. There are kits made to do this, then you can top off without tea spooning in the last few gallons.
Personally I havent spent the time to do this. Tank is big enough. If I really need more fuel I'd put in a slip tank.