Hi,
It is possible for coolant to very slowly evaporate, but being in a sealed system usually prevents it from happening.
As far as having to add coolant a couple of times really isn't a concern at this point. The radiator may have been low, so the first time you added, it drew it all in. Keep an eye on it and if it constantly goes low, let me know.
Since you are not seeing any leaks, I want you to read through this link. This isn't what I think is wrong, so don't worry. But I want to confirm the coolant isn't going somewhere you can't see. Read through it and do the checks you feel comfortable doing. Let me know what you find.
https://www.2carpros.com/articles/head-gasket-blown-test
Also, let me know what size engine the vehicle has. It could be a 4 cylinder or a 6 cylinder.
Take care,
Joe
SPONSORED LINKS
Monday, June 14th, 2021 AT 9:48 PM