>> Transmission stop leak will swell the rubber seals in the transmission. Heat >> kills the rubber. >How about leaks in the power steering pump and steering box? Could this >stuff be used to swell those seals, too? Could this damage the steering >system? > >George Clineman I have no personal experience with any product that is intended to stop leaks in power steering systems. Power steering leaks are most generally the result of wear, contamination and seals deterioration inside the assembly that allows housing pressures to build well beyond the capability of the external seals/gaskets. This can also be totally true for automatic transmissions. Pour in, cure something products may work. The probability of success will depend on how lucky you are. When something is poured in, the chance is always there that the product may well create other, and sometimes more serious, problems. In our shop, my wife and I are faced with miracle additive questions on a regular basis. Per OEM instructions, we do advise that there are some that must be used. Techron is one that is specifically recommended by Volvo for Bosch injector PM. GM has an injector product and says OK to Techron that must absolutely, positively be used to keep their Central Sequential FI system working. Used or not used we have seen the systems go down so what is the answer? Ginger root for block/coolant sealer: Really old technology; now OEM GM, Ford, Chrysler. Sta-Bil for fuel system storage OK. Top engine cleaner? For some engines this is a must but I still see head removal as the only effective way to decarbon combustion chambers and head ports. Therefore, if you absolutely must, go ahead and pour. I shared one product name that we have not seen to be destructive with older design automatics and that product also says OK for power steering BUT - - - - This is one shop owners opinion, and, - - - I could be wrong. Warren Anderson Sedona,AZ