I accidentally put windshield washer fluid in the coolant reservoir

I accidentally put windshield washer fluid in the coolant reservoir of my friends 2015 Altima. I was borrowing it and a light came on saying it was low. I put maybe a 1/4 gallon or less in. Will it cause any damage? Do I need to try and take it out? Do I need to do anything or will it be fine? Please help!

First you need to tell your friend what you did. Then do what ever the friend wants you to do.

My car, I would not worry about it.


It wont harm it, but you do need to tell your friend because the windshield washer fluid contains alcohol which will boil off pretty quickly, leaving them low again. If they live in cold country, they should add a little pure antifreeze when topping off next time as the remaining water from the washer fluid will have diluted their coolant.

Ritual seppuku is the only honorable response.


Your friend should be concerned with why the coolant was low. I agree with the above posts and suggest you advise your friend to have his cooling system closely inspected.

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I think the OP meant the low level light for washer fluid . It might be a good idea for the owner to check all fluids after loaning a vehicle to someone.

The Altima has a 9.5-quart capacity and you put about 1 quart into it. I doubt a 10% fill with a different type of antifreeze is a problem. If you still have the windshield fluid bottle, let us know what the ingredients are and maybe we can determine if any of them might corrode the radiator.

It would be best to suck out the contents of the coolant reservoir with a turkey baster, and refill with the correct 50/50 coolant.

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Don’t worry about it.

Washer fluid is water mixed with ethyl alcohol and a blue dye. So it’s mostly water once the alcohol evaporates.

Now if you had put coolant into the windshield washer reservoir?

You’d be taking that system apart.


I’d spring for a coolant flush if I did that to a friend’s car myself. Not so much b/c I thought the one quart would cause a problem, but b/c if any problem at all happens involving the cooling system in the future, I’d want to be able to say I wasn’t the cause. In the meantime the ability of the existing coolant to withstand the lowest temperature in your area should be tested.

Was it the WW washer fluid that the warning light said was low? Or was it the coolant that was warned as low?

I’ve never bought, but when I looked at the ingredients they’ve had methyl alcohol, not ethyl.

And that is why I just wrote alcohol in my post.

Sorry for the typo.



I didn’t respond to your message.

Heet is methanol; Isoheet is propanol: wouldn’t propanol be a safer ingredient for windshield wiper antifreeze?

My Toyota’s manual tells me that water is okay as long as it doesn’t get cold enough to freeze. I make my own winter version with water, propanol, and ammonia.

Safer, yes, but isopropanol has a penetrating odor that might be irritating if it wafts into the cabin.

Which poison is safer? Methanol and 2-propanol will both kill you in small doses.

I agree with @insightful that IPA produces a disagreeable odor in the passenger cabin when used in windshield wiper fluid. I made my own with IPA once, and didn’t like the odor at all.

Millions of people breathe propanol every day. Methanol smells better?

Metabolic Acidosis in a Patient With Isopropyl Alcohol Intoxication: A Case Report

’ It has been reported that the lethal oral dose [of methanol] is between 143 and 6,422 mg/kg’ CDC - Immediately Dangerous to Life or Health Concentrations (IDLH): Methyl alcohol - NIOSH Publications and Products

‘The probable lethal oral dose [of propanol] has been reported to be 190 grams’

Methanol smells much better…ever smell blue winter washer fluid (probably 40% methanol)?

I’ve always made my own - and never huffed it. I remember the wood alcohol of my childhood smelling a bit sweet. My windshield is uncracked, my doors seal: I don’t smell what I squirt on the windshield.