Lubegard 19610 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. Instant Shudder Fixx is compatible with all conventional or synthetic automatic transmission fluids. For long term transmission benefits, also use Lubegard Synthetic ATF Protectant (Part Number 60902, sold separately). To use Lubegard 19610 Instant Shudder Fixx: While holding the tube, cut off the tip end, and empty contents directly into ATF via dipstick tube, or fill-port on the side of the transmission. Then drive normally.