Simply put, my friend was adding washer fluid (wanted to try rain-x) to his g35 before we went out in the rain and somehow managed to add it to the coolant overflow container. By the time I noticed and told him to stop, there was already about an inch worth of fluid in the overflow container. What will happen if he leaves it there?

 

if it's an inch only,I don't think anything will happen.. you said the overflow container? I don't think it will go back into circulation in the system ( hence the term overflow container)... however, I could be wrong.

 

just take out the overflow container, drain the fluid, and fill up with with coolant

 

You know what you must get rid of that car now... its ruined. Please have it delivered to my house promptly

 

One question: Is the vehicle leased? If so, sorry NMAC, but I wouldn't worry about it.

If it were my own car, it'd drive me nuts. If you haven't driven after it happened, just siphon out the overflow. If it's been driven, then the fluid has mingled with the coolant. An inch is not much, but I'd want it out of there. If I had to take a wild guess I'd say it's harmless because washer fluid has to be able to hit the paint of the car and not destroy it.

 

Coolant typically consists of 50% water and 50% anti-freeze (Ethylene or Propylene Glycol). Washer fluid, on the other hand, is mostly water with a small percentage of cleaning agents. You'll have to look on the bottle for exact contents. I don't know about the G35, but the total coolant capacity should be huge compared to the percentage of cleaning agent in the washer fluid that got into the system (literally a drop in the bucket). Normally, I would say that it's nothing to worry about. Even if you poured an entire bottle in, it's still mostly water. So at worst, your engine won't be protected from extreme heat or cold.

However, it also depends a lot on the chemical composition of the washer fluid. Since most internal engine surfaces were not designed to tolerate harsh environmental conditions, they are probably just bare metal. These surfaces may be very susceptible to corrosion. Additionally, if there was any alcohol or other organic solvents in the washer fluid, it could make rubber seals brittle over time. Keep in mind that these effects won't be catastrophic. We're probably talking minuscule changes years upon years from now if you left the contaminants in until your next coolant change. But not knowing what you're dealing with, I'd say the safest way to go is to drain the radiation, fill with distilled water or flush, run it, drain it, then refill with pre-mixed anti-freeze according to the owners manual. Small price for piece of mind in my book. Hope that helps. Good luck.

 

It'll probably help to keep the radiator channels clean.