I have had my leak for a good 6 months now. Its slow, makes a mess but car seems fine but there are spots of oil in the coolant. And it gives the car a funky smell on the outside because of the burning oil on hot engine parts.

I know ill get it fix but it wont be anytime soon. Could be even 2 years before I even get around to actually address that problem again.

So to answer the original posters question I will take my car to 2 years or even longer with a leaking headgasket. Its already been 6 months and my car is a daily driver 100 miles a day