Changing the fluid in your Jeep JK Wrangler’s differentials is an important part of routine maintenance. New gear oil will insure your differentials will be well lubricated and function properly. And, unlike previous Jeep Wranglers, it will not be necessary remove the differential cover in order to do this. Granted, I do recommend that you do so anyway from time to time (every other fluid change) as it will give you a chance to inspect your gears and catch any damage or unsual wear.
Following "Schedule B" in the Jeep owner manual (heavy driving), I change my differential fluids every 15,000 miles. However, It’s always a good idea to do this as IF you've submerged your axles in deep water for prolonged periods of time. Below is a list of what you will need and instructions on how to service yourself differentials on a Jeep JK Wrangler Dana 30 or Dana 44 axle.
What You Will Need
• 3/8" Drive Ratchet
• Torque Wrench
• 3" Ratchet Extension
• Oil Catch Pan
• Paper Towels
• (4) Quarts 75W90 or Heavier Gear Oil (Use synthetic IF you have a limited slip differential)
Differential Fluid Capacity
Front Dana 44
2.7 pints (1.35 quarts)
Rear Dana 44
4.75 pints (2.375 quarts)
Basic Fluid Change Instructions
1. Using the square head of a 3/8" Drive ratchet, remove the fill bolt from your differential cover.
2. Place an oil catch pan underneath your differential. Then, using a 3/8" drive ratchet with a 3" extension attached to it, remove the drain bolt from the base of it as shown.
3. Allow your differential to drain completely before proceeding.
4. Your Jeep JK Wrangler’s drain bolt is magnetic and the inside end of it should be fuzzy with fine iron filings. Use a paper towel and some brake cleaner to wipe the bolt clean.
5. Using a 3/8" drive ratchet with a 3" extension attached to it, reinstall your drain bolt back on to the base of your differential. Tighten this bolt to 25 ft. lbs. of torque.
6. Proceed to refill your differential with gear oil. Please note that a front Dana 44 differential only needs 2.7 pints (1.35 quarts) and the rear only needs 4.75 pints (2.375 quarts). If you have factory covers, all you need to do is fill up your differentials until gear oil oozes out of the fill hole. If you have an after market differential cover that has a higher fill hole than factory, DO NOT be tempted to add any more gear oil than is needs. Doing so will result in a differential that is over-filled that will cause gear oil to get pumped out of the breather tube. If you are unsure how much you'll need in your axle, a good rule of thumb to follow is that you only need as much gear oil as is needed to get it to reach the bottom of your axle tubes. You can use a zip tie bent in a 90° angle to act as a dip stick to help you know where that is. NOTE: IF you have a limited slip differential, you will need to add friction modifier into your differential or, be sure to use a synthetic gear oil as it will have friction modifier in it.
7. Using the square head of a 3/8" Drive ratchet, re-install the fill bolt on to the differential cover. Tighten this bolt to 25 ft. lbs. of torque.
Thorough Fluid Change Instructions
In order to perform a thorough differential fluid change, you will be required to remove your differential covers. For instructions on how to do this, simply click on the link below. While it was written for the installation of aftermarket differential covers, the process is the same.
Differential Cover Installation Write-Up
That’s it! Please let me know if you have any questions and don’t forget to take your old gear oil to your local recycling center (PepBoys, Autozone or the like).