This is a 50ml bottle of Mugen 80,000 wt Silicone differential oil for 1/8th scale off road buggies, trucks and any other vehicle with a fluid filled differential. The thicker the oil, the less your differential will "diff out" in the corners, where the two tires will turn at different speeds. Changing the diff oil in your diffs is one of the most important tuning options for off-road vehicles.corners, where the two tires will turn at different speeds. Changing the diff oil in your diffs is one of the most important tuning options for off-road buggies.