Jeep Cherokee XJ - Manual Transmission AX-15 Fluid Swap

The fluid in the AX-15 manual transmission is really easy to drain and refill. It should be drained every 30,000 miles. With the proper tools and a bit of patience, this can be done with very little effort. For me, most of the time spent was doing research.

Using the Proper Fluids

Selecting the correct fluid is the most important part of changing the transmission fluid. The AX-15 transmission only takes 75W-90 GL3 or GL4 gear oil. Do not use GL5! GL5 gear oil typically contains sulfur compounds as an "Extreme Pressure" lubricant. At high temperatures, sulfur degrades copper-based metals. The AX-15 has bronze (copper-based) synchronizer rings and bushings.

If the wrong fluid is used, the bronze parts of the transmission will disintegrate. Obviously, this is not good!

Searching the web, I stumbled upon many forum posts like this one on JeepForum. The highest recommended brand I've seen for 75W-90 GL4 gear oil for the AX-15 was Red Line (50304) MT-90 75W-90 GL-4 Manual Transmission and Transaxle Lubricant. The capacity is just about 3.5 quarts, so I bought 4 bottles.

Draining the Fluid

Get under the vehicle and place an oil pan underneath the passenger side of the transmission. The lower drain bolt will be on this side. The fill bolt is up a bit higher on the driver side.

First, remove the fill bolt with a 24mm socket wrench. I had some trouble getting this thing off, it was on there tight! Be patient, and use a breaker bar if you have to.



Once the fill bolt is removed, move over to the passenger side and remove the drain bolt. Be ready, the fluid will shoot out.



When the transmission is finished draining, put the drain bolt back on and tighten it to about 20 ft. lbs. of torque. Back on the driver side, use a fluid pump to reach up to the upper fill hole and start refilling. Be patient, depending on the pump, this could take quite a bit of time.



The transmission is full when fluid starts overflowing from the fill hole. At this point, put the fill bolt back on and tighten to 20 ft. lbs. of torque.

Congratulations! The transmission fluid is replaced. Happy wrenching!