The Stovebolt Site Forums The Shop Area The HiPo Shop T-5 Question

There are two types of t-5s, basically.

There are the the World Class t-5 and the 'Non-World Class" (WC v. NWC)

The Non World Class is the original and has brass syncros. All the Astro-van/S-10 t-5s are Non-World Class and need gear oil. Most of these have 14 spline input shafts.

The World Class came later and has better bearings and composite syncros. The early camaro/firebird T-5s were NWC and the later ones are all WC. Most of these have 23 spline input shafts.

With Brass Syncros, gear oil. (Non-World Class)

With Composite Syncros, ATF. (World Class)

ATF will probably work in a Brass Syncro Tranny, but gear oil in a composite syncro tranny ain't a good idea. The Brass Syncro Tranny will shift a lot smoother with gear oil, and probably stand up longer too.

There are probably even odds that someone put ATF in your brass syncro tranny, and if that is the case you should use a tranny fluid flush product before swapping back to Gear Oil. ATF and Gear Oil don't mix too well and you'll get globules.