Joe, like bigbad said, hopefully it has the wrong type fluid. The T5 was produced for over 20 years and had many changes. first you need to know what the tranny came out of and what year. Chevy, F**d, Jeep, AMC, and Eagle all used the same T5.
The biggest misconception is that all T5's take gear oil. There are two classes of T5's, World Class and Non World Class. Non world class were a modified T4 4speed with 5th gear added as an after thought and your gears ride on a solid shaft with no bearings so they must use
70 weight gear oil. These were found in early S10 Blazers and Astro vans made before the mid '90s. For some reason the Camaro/Firebird got the World Class trans but the S10/Astro didn't.
The World Class uses
Automatic Transmission Fluid Only. Camaros and Firechickens from '88 up and got this one which switched to bearings between the gears and shaft so it must use ATF to keep everything lubed. Just about everything from mid '90s and up were World Class T5's.
If you aren't sure which one you have look for either a stamped tag on the case or numbers stamped directly on the case. You can either call your chevy dealer, look it up on the internet or just email me and you'll be sure that you're using the correct fluid. I researched all this after I found out the hard way when I used ATF in my NWC and wondered why it spit out the gears.
On the bright side, if your trans is bad (which it really doesn't sound like), you don't have to limit yourself to just a Chevy as a donor. You'd be surprised how many T5's are out there being overlooked and they are cheap and plentiful. So don't get suckered by some bonehead who thinks he is selling you gold or something.
I just scored a new bellhousing on Ebay yesterday so I can put my T5 in my '55 wagon. I hope this clears up a little for you. If you need anything else, just ask.
Good luck,
Scott
