Marcy, it sounds to me like you don't really understand the purpose of the differential. Basically, it's to let the wheels rotate at different speeds while the truck is turning. If you want to know more details, this is a pretty good explanation: http://auto.howstuffworks.com/differential.htm In the LST, the viscosity (thickness) of the diff oil controls how easy it is for the wheels to rotate at different speeds. Thicker oil = more difficult for them to rotate at different speeds, thinner oil = easier to rotate at different speeds.

Like I said, I can't really see diff oil affecting your ability to wheelie if you're using any of the common weights.

I can't really answer the question about the LST wheelies, I'm just on breakin with mine. Most people here have said though that it's very eager to wheelie.