When to sell is a very personal decision. It is not cheaper to buy a new car. If this were true, only poor folk would be driving new cars.

I dont think you have a head gasket problem. A leak from the front means you need a new upper timing cover seal... a much cheaper fix.

The time to let go of the car is usually when the body starts to deteriorate beyond what is acceptable to you. Mechanicals can usually be dealt with.

__________________
95 E320 Cabriolet, 169K