Re: Wynns stop leak $12.00 @ bp
On the topic of Radiator Leak fix products.... (which I also mistook this thread to be about)
I reckon they should never be used.... unless you are stranded.
Although they do work in most cases, deposits can build up wherever, this can reduce the overall efficiency of your cooling system.. kind of like clogging or hardening of your arteries.. and you may eventually starve or block off portions of your engine from being effectively cooled resulting in even more expensive repairs.
Once you add them to your cooling system you'll never get rid of the deposits in the parts of the engine that don't need them.. so I suggest you never use them.