What you experienced is driving the car into the ground till its junk and then trying to fix it by installing one or two pieces.
Like installing a radiator tank, you should install a new radiator and if you had been using coolant since new, it would have been leak free till now.
Same as you paid labour to install new tappets, when you could have bought a set and had them installed earlier on gasket job.
Its called being economically smart, a car should be your servant and not the other way round.
