knocking sound

I have a 1991 chevy caviler, my problem is I get this knocking sound when the car is on. The oil is full and does not seem to be leaking at all infact I never had to add any becuz the stick says its at the level its suppost to be, but it ticks....and when I 1st start the car there is nothing for about 10 seconds and then i get this noise. Does anyone know what it could be? It is driving me insain.

maybe it is a relay, they click when they are bad sometimes, it could also be your spark plug or your lifters going bad, you should definatly have a professional check it out, alot of them are good at telling what's wrong just by listening to it

turn the car on and listen where its coming from, if its from the head from the engine, you blew a piston and posibly the engine is f*****

well it could be just the lifters. they do burn up and go bad,