Not overfill. Forgot what its called. Need to open the valve cover. Every plugs inlet on the valve cover has a seal to prevent oil from the head escape to the spark plugs inlet. When its harden, oil will seep through. Mechanic normally will apply loads of sealant before fitting the valve cover. I believe OEM fitting is without sealant. With sealant, the rubber seal harden also no need to change.... until its brittle and give way..
Malaysia cheap maintenance style! :top:
Confirm no white smoke from exhaust ya? If got white smoke or wet/oily tail pipe, then replace your valve seal at one go.
If running on tight budget, no need to bother except toping up of engine oil once the level is too low. Again, cheap Malaysian maintenance way..