1998 Chevy Cavalier oil check lite comes on when pressin br

Check the oil pressure with a mechanical gauge if normal replace the oil pressure switch abnormal could mean oil pump and engine bearings.

With the info you have provided I would say you may have an oil leak. Also if the light comes on that means you are having a drop in oil pressure. It could be mechanical wear of the engine or it could be the wiring to the sending unit or the sending unit it self. Put some STP oil treatment in it and look for leaks. If you have no leaks and continue to get an oil light you are in danger of having major engine damage.