Rep Power: 0

So I have a Civic that has been sitting for the past few months, and I had to suddenly drive it the other day due to problems with another car.

It was around 0F outside and had to jump the car. I also topped off all fluids and let it warm up for about 15 minutes. I know this is a terrible scenario for driving a car that has been idle for a while.

Two days later, it suddenly started to overheat at low RPMs. Temp would regulate around 50mph, but would spike severely and steam when stopped at a light (which upon opening the hood, showed that the coolant had boiled out of the reservoir). I only drove it for about 15 minutes as I was stuck on a highway with no exits. Also not a great scenario.

I hoping there is no sever damage, but doesn't anyone have an idea where to start based on the specifics?

Thanks!

 
Rep Power: 518

Head gasket.