I got bored yesterday and decided to change the fluid in my YJ's NP231. I unscrewed the top bolt to see what condition and level the fluid was at. As soon as i got it off, it started pouring out thick, dark grey sludgey goop. I got out as much as i could, but im sure there's more lurking around in there. I'm going to drain it and refill it again this weekend. A couple of years ago, i got into some high water and filled the tranny (auto) with water. It was bad enough that i had to take it to a shop to do a complete flush. He said he flushed the transfer case, too. I use 4wd all the time, never had a problem. Everything works as it should. What was also weird is it really smelled like gear oil, too. Could it be? Why would he do that? He also said he filled up my TF999 with Dex/Merc fluid, when every other person including Jeep uses ATF+4. He's got a good reputation and he knows what he's doing....but why would he put gear oil in an NP231?

 

He did cause he cheaped out or didn't know better.

Flash

 

WTF is a TF999?

 

TorqueFlite transmission.