I recently had my 1990 740 overheat and brought it into the shop. Upon inspection, I discovered that water was leaking out of the car at a rapid pace when replenished. After bringing it to the shop, the mechanic replaced the heat control valve and some surrounding hoses, citing it as one source of the problem. He also observed that the gasket was blown causing water and coolant to leak from the engine.

I have read some old threads relating to the use of Stop Leak to fix similar problems. It's an old car with nearly 230,000 miles, so I'd like to avoid a costly gasket replacement if possible (and would be satisfied with only a years extension of the car's life). Is the use of Stop Leak applicable to my problem? If so, what is the brand name of the product? And how is it administered?

Thanks,
Allan