[lincpimp]

It is best to just buy the correct fluid, as reading the last 2 posts has given me a headache.

Considering you have slight tendancy to wheely, you may have about the right fluid in the center diff now, maybe a bit too thick. If the front tires are growing huge the fluid is too thin, and if the truck wheelies then the fluid is too thick. I think some front tire growth is acceptable, as it will help pull the truck around corners. The pro nitro racers run light fluid, and go thru a set of front tires in a single race... I noticed this when looking at the race action pics in the rc mags, and checking out the racer's riders section they usually do on the national race winners.

I run thicker fluid as I like wheelies (no racing for me!) and really like tires to last...