Instant Shudder Fixx Friction Modifier is the number one transmission instant shudder eliminator used by more professional transmission technicians. This is a five time concentrated friction modifier formulated specifically for eliminating transmission shudder problems instantly. In order to use it, the contents should be emptied directly into the ATF (automatic transmission fluid) via Filter Tube and then drive normally. The results will be immediate. instant shudder fixx is compatible with all conventional or synthetic automatic transmission fluids. It is for the best overall performance and long term transmission benefit. The Lubegard automatic transmission protectant is recommended to be used as well for long term benefit (Part Number, 60902. It is sold separately).