Changing the fluid in your Jeep JK front and rear differentials is an important part of routine maintenance. Fresh gear oil insures your differentials are well lubricated and function properly. And, unlike previous Jeep Wranglers, it is not necessary to remove the differential cover in order to do this. It is however recommended that you do so anyway from time to time (possibly every other fluid change) as it will give you a chance to inspect your gears and catch any damage or unusual wear.
Following “Schedule B” in the Jeep owner’s manual (heavy driving), you should change your differential fluids every 15,000 miles. However it is always a good idea to do this IF you’ve submerged your axles in deep water for prolonged periods of time. This post will provide instructions on how to perform a Jeep JK differential fluid change that applies to either Dana 30 or Dana 44 axles.
Front Dana 44 differential needs 2.7 pints (1.35 quarts) and the rear 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 needed. Doing so will result in a differential that is over-filled and will cause gear oil to get pumped out of the breather tube, creating a stinky mess. Gear oil level only needs to reach the bottom of your axle tubes.
NOTE: Rear differentials with Trac-Lok (limited slip clutch type differential, not used on the Rubicon), require the limited slip additive for the clutch plates. You can also use synthetic gear oil as it will have friction modifier in it.
Jeep JK Rubicon requires regular gear oil. The Rubicon uses Tru-Lok which is a mechanical lock to lock the left and right axles together. Tru-Lok does not have clutch plates, so an additive is not required. In the Rubicon with Tru-Lok differentials, when the rear differential is not locked, the vehicle uses the TCS (Traction Control System) to monitor the amount of wheel spin of each of the driven wheels. If wheel spin is detected, brake pressure is applied to the slipping wheel(s) to provide stability. This feature of the TCS system functions similar to a limited slip differential and controls the wheel spin across a driven axle. If one wheel on a driven axle is spinning faster than the other, the system will apply the brake of the spinning wheel. This will allow more engine torque to be applied to the wheel that is not spinning. This is how the Rubicon gets by without a limited slip rear differential.
As with any other fluids, refer to your Jeep owner’s manual for the recommended gear oil viscosity. I own a 2012 JK Rubicon, with both front and rear Dana 44 axles, and the recommended gear oil is 80W-90.
Differential Fluid Capacity:
Jeep JK Rubicon front Dana 44 2.70 pints (1.35 quarts)
Jeep JK Rubicon rear Dana 44 4.75 pints (2.375 quarts)
Non Rubicon front differential 2.10 pints (1.05 quarts)
Non Rubicon rear differential 3.80 pints (1.90 quarts)
Disclaimer: Like I always mention I am not a professional mechanic, I just try to do as much work on my Jeep as possible. It helps me learn more about my vehicle and save some money that can be spent on parts and upgrades.
I take no responsibility for any injury or breakage which might occur if you decide to follow these steps. You have to decide if you’re comfortable working on your Jeep. If you’re not, please have a professional complete this project for you.