Amsoil recommendation for the M6
 

Amsoil lists 3. Which one is best? I have Signature Series ATF in it now.
Manual Transmission,TR6060 (6-SPD)......GLS [2]
All TEMPS......
Signature Series Multi-Vehicle Synthetic Automatic Transmission Fluid (ATF) (ATFQT)
OE Multi-Vehicle Synthetic Automatic Transmission Fluid (OTFQT)
Torque-Drive Synthetic Transmission Fluid (ATD1G)

Signature series ATF. You won't be able to kill this oil with any obsurd amount of track abuse.

I have torque drive in mine, what's the difference Andy? Is it just more heavy duty?

Torque drive is perfectly fine and it is a robust oil. I like signature series personally for the following reasons, the ability of signature ATF to keep the metal to metal contact is a tad better than torque drive, signature series will last for ever being a high quality synthetic fluid, after 100,000 miles all additives were found to be intact during testing.
Very robust oil.

Cool i already have the best.

I just changed to the Signature Series ATF for mine and cold shifting is much better. When hot the difference isnt as noticeable but still smoother.

I'm happy with the torque drive in mine. The only reviews I had found were corvettes using it and they were happy also. My car has 5k miles and never had a problem with the oem fluid but I just wanted to upgrade it.