I have a 1995 Pontiac Bonneville SLE with original UIM.
My questions is as follows:
I live on Long Island and conditions are getting much colder here now in the past few weeks, especially at night. What i'm noticing is that the antifreeze level in the overflow tank drops MUCH lower overnight as it gets colder out (or seems to) but when the car is fully hot it'* still at or very close to "Full hot" where it was late summer when the car was fully warmed up. Tonight I was driving and it was rather cold, about 35 degrees. I was driving the car all the way on open highway for about 30 mins and of course the heat was on, so the temp gauge stayed a little lower than usual. When I pulled up to my house and shut the car off I immediately checked the anti-freeze level cause i always worry about a UIM failure. This time I noticed it about 2cm lower than "full hot" but I was figuring maybe cause it'* 35 out and I didn't really let the car get even hot enough for the cooling fans to come on cause of the weather. Can someone tell me if this is simply a matter of outside temperature, or am I looking at a possible UIM on the way? If it can be a UIM, can you tell me what other symptoms to check for to be certain, and about how fast these fail also from noticing these symptoms?
Thank you ahead of time to anyone who gives their advice/wisdom...it is highly appreciated.