Just use Diamond ATF SPIII
Just changed trans fluid. Went cheaper route and used the Castrol import synthetic. The trans didn't like it. Caused very bad shudder. The Castrol did state that is an equivalent to the Diamond SPIII (ass holes). Had to add Lubegard Platinum ATF Protectant. Still had shudder but somewhat improved. Then added Lubegard - Dr. Trannys Instant Shudder Fixx. Much better then, almost gone, however still episodes. Will need to completely replace the new trans fluid with the Mitsu fluid. Due to my cheapness, caused by unemployment, it is costing me double what it would have if I had just used the Mitsu fluid to begin with. I hate proprietary things but I hope there is a good performance reason for this.
Just some advise.
2003 GTZ with 106,000 and still a bad ass!