I accidently topped up my collant tank with a mixture of water and screenwash, used the wrong bottle. Probably only used about a cup full of screen wash. Will this damage the engine and should I drain the system or can I just leave it?

I started the car, but realised and stopped it immediately.

Gaz, February 2009

To be safe I'd drain the coolant system. Then add 50/50 mix, water to antifreeze.
The screen wash will prob be some kind of detergent, better to be safe than sorry. Wouldn't cause any immediate prob, thinking long term corrosion, head gasket etc.

George., February 2009

Shouldn't be a problem if you only put in a cupful.

Chicks Fan, February 2009