Just use a good trans merc dex fluid like valvaline. don't use store brands unless you research them and find out who makes them and if they blend it the same as the name brand. Valvaline makes napa preformance trans fluid and it's the same stuff as valvaline trans fluid. Don't use additives either. A good trans cooler will make that transmission last longer than the best top dollar oils on the planet. Keeping them cool saves thier lives. If it runs above 220deg your going to cook it slowly. 200 or less is perfect range for a trans. and 200 to 220 is about normal in the summer depending if you run a big stall or not.