Originally Posted by slaytanic

Without getting too technical, diffs work by transferring more power to the tires that are losing traction. So, look at the center diff. When you are on the throttle you may see your front tires baloon up. Thats because they are losing traction and the center diff is sending more power to the front. This actually slows your accelleration some. By putting a thicker fluid in the diff you slow this action down some and it keeps more power to the reaer giving you more bite. Too thick of a fluid though and you will get too much power to the rear causing the rear end to become loose and breaking free. This is cool if you want to do donuts but in racing you want to find a good balance. So, start with maybe 5k in the center and go up or down from there until you find what feels right. There is alot more too it than this but it will give you the idea. Do some reading and you will get it. Hopw this helps.