Pick which transmission fluid you use in your T56 that has improved shifting over the STOCK ATF fluid that you have had in your transmission for at least 1000 miles with NO problems. I will not be including Redline D4 ATF or Redline MTL in the poll because it has been proven to swell the carbon rings. Check out this information on a Firebird FAQ about the T56: http://www.cnyfirebird.com/showArticles.asp?ID=15 "THE Word" on 1998-2002 Manual Tranny Lubricant The question about whether one should run synthetic ATF or even a non-ATF gear lube in the f-body's Borg-Warner/Tremac 6-speed tranny has been bouncing around. Mark DeCarlo, co-organizer of CNYF, has tracked down the answer. Mark reports.... "I spoke with the T-56 expert at Tremec. He said that the Mobil 1 Synthetic ATF is an excellent choice for the T-56, PROVIDED that the T-56 is a 1997 model or newer. DO NOT run the synthetic ATF in the pre-1997 T-56 units. It will destroy the paper on the blocker rings. And do not run it in a manual trans with brass blocker rings either, because it will ruin those also. Tremec changed the blocker rings to the carbon fiber type for the 1997 model year and synthetic ATF will not degrade these. I asked about the GM SynchroMesh and he said it was good, but not quite as good as the Mobil 1 Synthetic ATF. The SynchroMesh fluid comes in the Tremec 3550. He said you should have no problems running the Mobil 1 Synthetic ATF in the T-56. Notice how I keep saying "Mobil 1 Synthetic ATF". He said stay away from the other aftermarket racing type synthetics, as they have extra additives that can degrade components. I asked about the Castrol Syntorq gear lube. He said you could use it (and they used to in the Viper), but you will encounter hard shift in cold weather and cold clash. I asked if GM would honor the warranty if something were to happen to the trans while the Mobil 1 Synthetic ATF was installed and he said they would. But the one thing I would like to point out; just because a bottle says that it supercedes a different product, doesn't make it necessarily so. If someone had grabbed the bottle of synthetic ATF and read that it meets and exceeds all dino ATF specs; and then installed it in their pre-1997 F-body, it would have ruined the box. So don't believe everything you read."