i use penzoil syncromesh or syncromax for gm vehicles, which ever one it is, and lucas oil stabilizer, and it works wonders. my third gear use to grind almost all the time, put this in, and havent had a problem yet, whether it be shifting hard or slow, always the same!! i would recommned this over anything else. tried redline, tried royal purple, tried mobil 1. this is the best out off all of them in my opinion!
craig