ATP AT-205 Re-Seal Rubber Seal Leak Stopper 8 oz

AT-205 Re-Seal is a pour-in additive that softens and swells the rubber seals and O-rings inside an automatic transmission, engine, power steering rack, or differential. When a case seam starts weeping or the pan gasket seeps ATF, this is the first thing to try before pulling the unit apart. It works on the front pump seal, output shaft seal, and the servo and accumulator O-rings that dry out and shrink with age and heat.

The formula does not contain petroleum distillates, so it will not over-swell seals or leave them mushy the way some stop-leak products do. It plays fine with conventional and synthetic fluids, so you can add it to Dexron/Mercon ATF, gear oil, power steering fluid, or hydraulic oil without a fluid change. One 8 oz bottle treats most transmissions and engines; add it to the existing fluid and drive it for a few hundred miles to let it circulate and swell the seals back to size.

Use it as a diagnostic step and a stopgap on higher-mileage units: if a leak stops after AT-205, you have bought time and confirmed the problem is a hardened seal rather than a cracked case. It is not a fix for a blown seal, a stripped pan bolt, or a cracked line, but for the slow drip on the garage floor it is the cheapest thing you can pour in.