The gear oil in a Jeep Cherokee's rear axle assembly can become contaminated over time due to water, heat and other elements, so it is a good idea to change it once in a while. There are also synthetic gear oils on the market now that offer superior lubrication if you choose to go that route. Remember to dispose of the used oil properly, whether through your local waste management service or auto parts store. The oil change can be done fairly easily with common mechanic's tools.
Drain the gear oil from the differential by loosening a few of the bolts on the bottom of the differential cover then inserting a flat head screwdriver into the gap. Place a drain pan under the housing and pry the cover up just a little. When the oil has drained, move the pan and put it safely away where it won't get kicked over.
Remove the rest of the bolts and take off the cover. Use a clean rag and wipe out the housing to ensure that any debris is removed before replacing the cover. Scrape the gasket surfaces on both the housing and the cover with the flat blade screwdriver, razor or knife.
Replace the differential cover and fill with oil. Lightly coat the gasket on both sides with RTV silicone then place the cover back on the housing, with the gasket in between. Reinstall the bolts but only turn them as tightly as you can with your hands until the gasket silicone dries. After an hour or so, the silicone will be tacky enough to tighten the bolts down the rest of the way. Once they have been tightened, remove the fill screw in the middle of the differential cover and pour in gear oil. Add it very slowly until it just begins to seep back out of the hole then reinsert the plug. Inspect for leaks before driving the Jeep.
