1990 GMC Transfer Case--What Fluid Does It Use? Help Quickly, It's Very Low

[ZZ]

I took my truck to Wal-Mart for the 4,000 mile oil change today. The tech said my transfer case is very low on lube. He said that GM used a synthetic fluid in these models and they didn't have any. I thought they used regular 80w/90 gear oil like the rear end uses. But from what I can find here through the board search is that the case uses ATF or the likes.

Did/does GM use a special fluid for the transfer case?

[john8662]

Consult your manual if possible.

But they usally all take ATF, use the same trany fluid you put in your transmission, the Dexron.

[NH2112]

For the most part, 3500s used the NP205 gear-driven case and these use gear oil. Everything else used either the NP208 (Blazers & Subs up to 91) or the NVG241 (all other 1500s/2500s) which require ATF. An easy way to tell is if the case is aluminum it uses ATF, cast iron takes gear oil.

[ZZ]

Thanks Guys. I'll take it back to Wal-Mart Monday and tell them to fill it with Dexron.

[ZZ]

I went back to Wal-Mart Monday. They had two cars on the oil change pit with one waiting and then one car in the tire area ahead of me. The Dept manager said he only had one guy working and that it would be an hour or two plus wait.

So, I went to a tire chain called Plaza Tire and asked them to add the needed Tranny fluid to the case. Their tech pulled the plug and stuck his finger in it. He said it wasn't very low but it did have oil in it instead of fluid. I didn't know what to do. I didn't really know how long it had been in there; so I had him to put what it needed to bring it up to the plug. He pumped the handle three times. I went in to pay and they charged me $19.95 for a full lube job. It looks like I'd learn to ask before I jump the gun and have things done in a big fizz.

I took it today to the Tranny shop who rebuilt my 700R4 and asked their opinion. The guy suggested that they check where the leaks are and then drain it and then refill it with Dexron. I left it with him to do the job. I went back at closing time to check on it. He showed me that all the gaskets & seals were seeping. He wanted $150 to $200 to tear it down and change all of them. He said that if it was his and babied it the way I do and never use the 4X4 that he'd just let it be and drive it. He said it's lasted this long, and it would most likely be Ok for a good long while.

I don't know why sometimes the craziest BullSh*t happens to me all the time. But oh well. Life goes on... ;-)