What happens if some oil is put in the water coolant by accident?

Answer 1

I did exactly that last month putting about a 1/2 quart before i realized. As long as you havent started the engine use a siphon to extract as much of the oil as possible Drain radiator refill with clean water and use a prestone back flush kit, refill with 50/50 antifreeze and you should be alright I havent had any problems at all.