There is a lot of talk on Supraforums about using any other oil in the 6 Speed other than Toyota. A lot of people are switching over to Royal Purple Synchromax, and I decided to make that switch as well.
I feel I must post this after the replies, Toyota recommends V160 only in their transmission. It's a risk you have to take to experience better shifts if you would like to try the Synchromax.
Here is a picture of the RP Synchromax. You will need three quarts which will run you about 7 dollars per quart. Toyota V160 is THIRTY FIVE DOLLARS a quart.
Remove the bottom bolt from the Getrag 6 Speed transmission, you can see the bolt here, but remove the top bolt FIRST so the transmission can actually breathe and the oil will flow better..
Let all the fluid drain completely out of the transmission, and then replace the bottom bolt and use TEFLON on the threads to prevent any future leaks. Using a hand pump, pump about 2.25 quarts of Synchromax into the transmission through the top bolt. When it is full, it will overflow. Replace the top bolt and you are done. People say smoother shifts are on the way!