I have a 1995 Buick Skylark that overheats quickly when I drive for over 30 minutes or am idling in traffic. A mechanic looked over it and said it didn’t appear to be leaking (losing coolant) though my low coolant light just came on. There is also an obvious antifreeze smell in the car. I replaced the heater core about 3 years ago. Any thoughts as to the culprit to the smell and overheating?
if you are smelling antifreeze inside the car it sounds like the heater core (or the installation of the “new” one is not tightened properly)
if you have a leak, then yes, the coolant is low.
if there is a leak you may have air in the system, which is making the coolant not abl to flow to cool in the radiator.
take the car to a radiator, AC shop. they will know how to diagnose, and repair with a minimum of guessing.
As noted most larger cities have a real radiator shop. Likely it will not be a chain. They are the place to go with your kind of problems.