OFNA Racing Silicone Differential Oil, 30,000 Wt Ofna bottle of 30,000 weight diff-lock silicone oil by OFNA Racing. Ofna bottle of 30,000 weight diff-lock silicone oil is used in gear differential, mainly used in off-road nitro buggies. It's used to slow and stop the differential action of the diff units, thus providing better output power to the drive train. INCLUDES: One Bottle of Silicone Oil 30,000