- City
- Biloxi
- State
- MS
Quick copy and paste from last year, when I first installed a T5:
"And after endless Internet searching, researching, and talking to mechanics, I finally chose an oil to put in my T5. If you get bored one day, just Google "T5 fluid". How I made my decision:
The FSM calls for regular gear oil. They then revised this to AMC Part# 8983 000 000. To confuse the issue, they later said that it is "OK to top off with gear oil, but complete fluid changes should only use 8983 000 000". Of course, you can no longer buy AMC Part# 8983 000 000. Chrysler, who bought out AMC, says that their Mopar 4874464 is equal to the AMC Part # 4874464. The Mopar stuff is a synthetic manual transmission fluid used in the NV 3500's and NSG370 manual transmissions. I figure that if my 05 Rubicon's manual transmission has lasted 125,000 miles with the Mopar stuff in it, should work fine in a T5. NOTE - World Class T5's must use ATF due to the friction bands of their synchronizers.
The Mopar Part # 4874464 can supposedly be replaced by the following fluids:
AMSOIL 5-30 Manual Synchromesh Transmission Fluid
Pennzoil Synchromesh (supposedly the same thing as 30 weight synthetic oil)
GM Synchromesh Transmission fluids
Royal Purple Synchromax
The Mopar stuff and the synthetics range from $12-$20 a quart. The Pennzoil is about $7 a quart.
I think the biggest issue is that the T5 has to have some type of fluid in it. I know people who have successfully used 80-90 weight gear oil and ATF in these non world class T5's successfully. For me, the ATF always seemed too thin and the gear oil seemed to thick. The Mopar stuff is just in between, as far as viscosity goes.
I personally think that the 80-90 weight gear oil is too thick for these transmissions. We can get away with it down here in the south, due to our higher temperatures. Also, after comparing the internals of a T5 (small bearings, small oil ports and passages) to the other gear boxes I have built (Dana 20, Dana 300, T176, T150, T18 which all have much bigger bearings and oil passages) I think the thinner oil is the right choice for the Jeep non world class T5.
Well, that's my theory anyway"
"And after endless Internet searching, researching, and talking to mechanics, I finally chose an oil to put in my T5. If you get bored one day, just Google "T5 fluid". How I made my decision:
The FSM calls for regular gear oil. They then revised this to AMC Part# 8983 000 000. To confuse the issue, they later said that it is "OK to top off with gear oil, but complete fluid changes should only use 8983 000 000". Of course, you can no longer buy AMC Part# 8983 000 000. Chrysler, who bought out AMC, says that their Mopar 4874464 is equal to the AMC Part # 4874464. The Mopar stuff is a synthetic manual transmission fluid used in the NV 3500's and NSG370 manual transmissions. I figure that if my 05 Rubicon's manual transmission has lasted 125,000 miles with the Mopar stuff in it, should work fine in a T5. NOTE - World Class T5's must use ATF due to the friction bands of their synchronizers.
The Mopar Part # 4874464 can supposedly be replaced by the following fluids:
AMSOIL 5-30 Manual Synchromesh Transmission Fluid
Pennzoil Synchromesh (supposedly the same thing as 30 weight synthetic oil)
GM Synchromesh Transmission fluids
Royal Purple Synchromax
The Mopar stuff and the synthetics range from $12-$20 a quart. The Pennzoil is about $7 a quart.
I think the biggest issue is that the T5 has to have some type of fluid in it. I know people who have successfully used 80-90 weight gear oil and ATF in these non world class T5's successfully. For me, the ATF always seemed too thin and the gear oil seemed to thick. The Mopar stuff is just in between, as far as viscosity goes.
I personally think that the 80-90 weight gear oil is too thick for these transmissions. We can get away with it down here in the south, due to our higher temperatures. Also, after comparing the internals of a T5 (small bearings, small oil ports and passages) to the other gear boxes I have built (Dana 20, Dana 300, T176, T150, T18 which all have much bigger bearings and oil passages) I think the thinner oil is the right choice for the Jeep non world class T5.
Well, that's my theory anyway"

I might have to take you up on that for my stock green Scrambler


For instance, while at the National in Kentucky this year, I was getting on it pretty good while going up a muddy/loose rock hill. It probably took about 15-20 minutes to get past this obstacle, and the whole time, the poor T5 was getting throttled pretty good. Last year in Michigan, while playing on the sand dunes, the 4:1 gears in the Dana 300 resulted in quite a bit 3,000+rpm's being sent through the poor T5 for two days. Plus, I have drove this Scrambler at high speeds (75-80mph) from Biloxi, MS to: Moab, UT, Kentucky, Michigan, Missouri, and all over AL-LA-MS and parts of Florida. I don't necessarily "beat" on them, but maybe they just wont hold up to my Scrambler/my driving