If the leak is from a p/s hose or a bad enough seal leak within the p/s pump, there is no stop leak avaiable to stop the leak. Some stop leaks work ok at swelling seals to keep them from seeping, but this is never a complete repair. I consider that just a bandaid at best. If you want to try a p/s stop leak try the one from Lucas. This is much better than the Prestone and will probably mix ok with the MB fluid.Just remember to stop the leak more than likely something will need to be replaced. You also need to remember that this system is under pressure and as the leak gets worse the more quickly the fluid will leak.