The Jeep transfer case oil is the same your car manufacturer recommends for your vehicle transmission. This might be Dexron II, ATF+3 or some other automatic transmission oil. You need to service both components at the same time because they are interconnected. Consult your car owner’s manual for the appropriate oil for your particular Jeep model, and then decide whether you need to add or replace your transfer case oil.
The back of your transfer case has a filler plug around the middle of the body, which you can remove to check the oil level and condition. If you need to raise the back of your Jeep to gain access, make sure to raise the vehicle into a level position--all four wheels on jack stands, for example--in order to verify the correct oil level.
Place a drain pan under the case filler hole. Loosen and momentarily remove the filler plug using a socket or hex wrench. If oil begins to drain from the hole, replace the plug immediately. The case has the correct level. Now, check the oil condition. If you detect dirt, water or other contaminants or there is no drain, you should replace or add oil, advices James E. Duffy in “Modern Automotive Technology.”
Some Jeep models come equipped with a skid plate located under the transfer case; you might want to remove this plate to replace the oil. If you decide to remove it, support the transmission with a jack stand, then use a floor jack to support the plate and proceed to remove the mounting bolts. This will give you wide access to replace the oil by removing the drain plug at the bottom of the case body. Otherwise, you can drain the transfer case and then wipe the skid plate clean.
When adding new oil, use a squeeze bottle, a bottle pump with a clear hose attached to it, or a yorker spout on the bottle of oil to refill the transfer case. When done, take your used transmission oil to your local auto parts outlet, service station or repair facility in your area for recycling.
