Changed Trans Fluid and Now Jumps out of Gear???????????????

71 CJ5 225 Dauntless and T90 or T86 Trany. Last week i drained the tranny and the fluid looked like thick chocolate milk. So i filled it again with Advance gear oil 85w90 and drove it for 2 days and then drained again. Of course it looked the same. SO i filled the tranny with Lucas Gear Oil 85w90. Since i drained it the first time it grinds when i am shifting to first and also jumps out of third everyonce in a while. WTF???? Please help this is my DD. Thanks in advance

 

The trans is a t14 if stock. Sounds like your syncros are going bad!! The thickened oil added enough friction for the worn syncros to work.

 

So can i use Lucas OIL in it? the bottle says i can but is it ok?

 

I have Lucas oil in mine and it works fine, been in there for about 3 years now.

 

Thanks i will try it.

 

My FSM calls for a GL 4 rated gear oil. I drained the GL 5 that was in there, and replaced with the recommended. My budding syncro problems went away.

 

bingo! i had the same problem with my t15, but as soon as i put dedicated manual trans lube in there the syncros quieted down and it shifts smoother than ever. Gl5 has a higher sulfur content which eats the brass snychros. Despite the fact that alot of oils say that they are GL5 and GL4, they cant really be both.

Get rid of the GL5, and put in redline MTL, True GL4 oil, or (like i use) BG syncro shift. It was a night and day difference after only a few minutes if driving. I'm sure there are other manual trans lubes available, but those will be your best options imho.