im about due to change the fluid in my t56, the dexron is a little too notchy for me anyways. 6speeds inc said to use M1 ATF but im looking to see what people prefer so which fluid have you been most pleased with?
post it up if I missed your brand

 

M1 all day long. lol Never had a problem.

 

I hate to say it but I switched to the Honda stuff about 6 months ago. Shifting was noticably smoother before I even got out of the driveway.

 

Mobil 1 ATF. That's what Six Speeds Inc told me to use and that's what I used. 8k miles and no problems.

 

Mobil 1 ATF now. Original factory fill changed to Valvoline ATF at ~ 1000 miles. Found the M1 on a local shelf at ~ 20,000 miles and changed. Didn't notice any difference after either change. The best change was replacing the factory wobbly-stick with the much better Hurst shifter.

 

I've tried just about all of them over the last 8 years and Honda Z1 ATF is the best.
T56 shifts smoother with the Z1 than any of the other stuff.

 

After getting my T56 rebuild by SixSpeedsInc (formerly T56Rebuilds), they recommended GM or Mobil1. Mobil1 was easier to find, so I went with that.

About 5000 miles on the rebuilt trans... no problems so far!

 

Mobil 1 ATF here.