At best, any of the "stop leak) additives will be a temporary fix. Here's the one we use her ein the U.S. and seems to work, at least on our tractors:
http://www.amazon.com...tiveASIN%3DB000ARPVNO
Sorry for the massive URL... You don't say what kind of car, nor do you say where the leak appears to originate. Most units are pretty much the same from car to car, since they are actually made by a second or third party and not the engine or car manufacturer. If the leak is coming from the front seal, the "stop leak" may help, but if it's coming from a hose (either supply or return) that's a different story. Hose leaks can, usually, be repaired mored readily.
Actually, the removal and replacement of the front seal isn't that big of a job, depending on the make of car, of course. But one has to know their limitations and tools available... Lotsa luck!