Improving the Shift Quality of your Jeep's Manual Tranny

By James Hasler

From Day 1 with my 94 Wrangler YJ, my AX-15 manual tranny would "crunch" into second gear and would flat out refuse to shift when really cold. I've heard a lot of good things about Redline's synthetic fluids so I gave them a call. The Jeep manual states that the AX-15 requires a 75W90 GL-5 lube. However, the people at Redline told me that most 75W90's are designed for hypoid gears such as the differential and are set up to be too slippery for the synchros in a manual tranny to work properly. So, Redline has what they call their 75W90NS GL-5 lube that was designed especially for manual trannies. Redline's 75W90NS fluid made a dramatic difference in shifting for my 94 YJ's AX-15. No more crunchy gears!! I thoroughly recommend it!

However, there are a lot of confusing and misleading info out there about what fluid to use where. Here's the info that I've compiled:

If you have an AX-15 (or AX-5 tranny in 4-bangers) tranny up to 1997, use Redline's 75W90NS gear oil

If you have a 98 or 99 AX-15 manual tranny, Chrysler changed the synchros and any GL-5 lube will corrode them due to it's sulfer content. The owners manual incorrectly states to use a GL-5 lube. The factory service manual correctly calls out a GL-3 lube. For this application, use Redline's MT-90 GL-3 manual tranny fluid.

If you have a 2000 Wrangler, Redline recommends a 50-50 mix of their MT-90 and MTL transmission fluids.

If you have an auto tranny, Redline makes a type 7176 fluid that Chrysler auto trannies require. For this, order Redline's C+ATF auto tranny fluid. The C+ATF is also used in the Jeep transfer case.

For your differentials, use Redline's 75W90 gear oil.

Check out Redline for more info on their superior synthetic oils. They also make the famous Water Wetter which can substantially reduce your water temp if used with an 80-20 water to coolant mix.