Hi,
That is a tough question to answer. What I would recommend is to get an antifreeze tester. With a tester you can determine both the freezing and boiling point of the coolant. That will identify strength.
I attached a pic below showing what I am referring to. They are usually under five dollars. On average, a 50/50 mix will provide a -45°F freezing point. Get one of these testers and let me know what you find. Also, here is a link that reviews flushing the system. You may find it helpful.
https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars
Let me know what you find or if you have other questions.
Take care and God Bless,
Joe
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Thursday, March 11th, 2021 AT 7:41 PM