Lube guard platinum, universal at fluid protectant.. Purchased at NAPA auto parts. Lube guard tech on phone said must use the platinum one, there are 2 lube guards at NAPA. It took a few minutes to figure out how to get trans cap off, Used a small mirror and a bent scratch awl to relieve red clip, you must push from back and gently persuede clip out. Put all 10 oz. in about two weeks ago and ALL tc shudder gone, also seems to shift smoother. Hope this helps everybody, took situation into own hands after DODGE said: idunno: " its normal, does it on all of them". PS Anybody got a fix for Grindy brakes.