2 in 1 Formula. Prestone ATF plus Stop Leak is scientifically formulated to keep transmissions running smoothly while stopping leaks. It is no ordinary transmission fluid. The Prestone proprietary 2 in 1 Formula is a blend of the latest in transmission fluid technology and advanced stop leak additives. 2 in 1 Formula: formulated for use in automatic transmission manufactured by General Motors, Ford, Chrysler and most foreign car manufacturers. Plus: powerful additives to help stop leaks and seepage due to hard, dry or cracked seals.