Poured a tin of Wynn's Engine Stop Leak into a Ford Focus ST?

And now the radiator is hot, very HOT, usually in cold weather I drive around full temp on the highest fan speed and its fine, after pouring this in the engine, it was on 24.5 on fan speed 3 and it was damn hot, couldn't take it.

What's happened.

What is that 24.5? Celcius?
Isn't normal 100 C?

Sounds like your stop leak intermingled with some residential crud and blocked a port or the radiator. You "F-ed" up your motor putting a stupid stop leak product in it. Nice playing mechanic? You probably now have a plugged radiator, heater core and the thermostat is going to also need replacing. Seems fine to me now, had to drive it hard up and down the motorway. If it was "f-ed" i'm sure there wouldn't be ice cold air coming out of it when you lower the temp… So much for mitsubishi techs.

You "F-ed" up your motor putting a stupid stop leak product in it. Nice playing mechanic? You probably now have a plugged radiator, heater core and the thermostat is going to also need replacing.

Seems fine to me now, had to drive it hard up and down the motorway. If it was "f-ed" i'm sure there wouldn't be ice cold air coming out of it when you lower the temp… So much for mitsubishi techs.