Seal Conditioners/Stop Leaks In Transmission Additives

I recently received an E-mail from a Fast Lube Operator that proposed a question about Seal Conditioners/Stop leaks in transmission additives. The operator simply ask “Are products that contain Seal Conditioners/Stop Leaks good or bad for automatic transmissions”?
Response: To answer this question correctly we must take a look at the automatic transmission as a pressurized hydraulic system. If a transmission is leaking from a seal point this usually means that seal is damaged and should be replaced. Adding products that claim to condition seals or stop leaks usually do so by containing chemicals that SWELL seals for a quick fix. The problem with swelling or expanding seals is that they will return to their normal state in time and your leak returns. This goes back to the old saying “What goes up must come down”. When seals are expanded through heat and chemistry, they can and will often dry out, crack or even worse flake depending on the seals compound.
Example Seal Compounds: Polyacrylate, Nitrile, Fluorinated, Silicone or Ethylene/Acrylic. This can cause multiple problems inside the automatic transmission such as pressure problems, hanging valves, contaminated fluid, plugging filters, coolers etc. Installing Products that contain seal conditioners/swell chemicals to stop leaks could have an adverse affect on proper transmission performance.