Put windshield wash in coolant dispenser, about 10 ounces any harm?
No harm done. Give it a splash of coolant so it doesn't freeze.
If you are worried about it then drain the system and install new coolant but there should be no harm. The real question is why are you losing coolant? If you are seeing a regular drop in the coolant level then take it back to the dealer as you have a warranty.
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