Jeep produces a large lineup of vehicles ranging from the Cherokee to the popular Wrangler. Most Jeep vehicles offer a four-wheel drive option, which includes the use of a transfer case and a front and rear differential. The transfer case uses the same transmission fluid as the transmission. The differentials typically use SAE 80w90 or SAE 75w140. Consult your owner's manual to verify the specific fluid type. Checking the front differential takes about 5 minutes and should be done when checking the transfer case or rear differential, or at least every 3,000 miles.
Locate the fill plug. The fill plug should be facing away from the engine on the smooth differential cover.
Remove the fill plug using the square head of the socket wrench. Use an extension as necessary. Some Jeep models come with a rubber fill plug that pops out by grabbing one edge and pulling.
Insert the small end of an L-shaped Allen wrench into the hole. Twist the Allen wrench slightly and remove it. The differential is full when fluid is present on the tip. Fill as necessary using the appropriate gear lube for your model of Jeep.
