My 3.1 98 Lumina also has a coolant leak it has 148k on it. I had already replaced the hoses as one was cracked which caused the engine to overheat once. Because of the overheating I think that is why its leaking coolant. It only happens when I'm driving and I dont see any visible external leak. I'm sure I've blown a head gasket but the car drives absolutely fine with no problems at all. I just have to top up the coolant everyweek.
My question is though will my car last just as long if I just top off the coolant when it needs to be? Or if I leave it will it turn into a bigger problem later?