[Madman762]

Unless you live in an area where it can get as low as thirty below zero, a good cooling system flush followed by a 50/50 mix of antifreeze and water should do it.

Most cooling system flushes say to run the car for 15-30 minutes with the flush and then drain the radiator. I tell people to run the car with the flush in it for a whole day or two, to give plenty of time for the flush to break up all the crap that's built up.