If you live in London, I would doubt that it never gets below zero degrees, therefore a small amount of tap water, would probably not dilute your coolant too much! However if you live where I do, it would matter.
A forum community dedicated to all UK Chevrolet owners and enthusiasts. Come join the discussion about troubleshooting, maintenance, modifications, classifieds, and more! Open to all models including the Captiva, Aveo, Spark, Kalos, and Orlando.