remove the driveshaft.clean the pinion flange with some brake clean.mark the pinion nut and the pinion flange with paint or something that wont rub off easy.only remove the pinion nut.apply a good bead of silicone and put nut back on.at times the gear oil is known to leak their.if the oil is between the pinion flange and the rear than change the pinion seal.if u attempt this yourself mark the pinion nut to the threads on the pinion shaft.this way you wont over tighten the pinion bearing.its really not hard to do.most of this information can be found online or most any real garage will print this information for you..even the dealer