Are you loosing oil? Meaning bumababa ba ang oil level mo and you need to regularly top it off.

Do you notice a constant bluish-white smoke from your tail pipe whenever you drive?

If your answer is yes to both, especially to the second question, then you need a top-overhaul.

The "typewriter" noise are probably your valves, you might need valve adjustment.

Cost? Kung valve adjustment lang, mura lang yan, kung top overhaul mahal.