98 cavalier with 60,000- miles and a new oil change and the add oil light is on even though it never was low on oil.

Sludge developing in the passages of the engine, including the oil sending unit? Remove the oil filler cap, look inside, and see what it looks like. If necessary, check out AutoRx. The safe thing to do is to check the oil pressure with a mechanical oil pressure gauge. This link may help:

https://www.askmehelpdesk.com/cars-t...ml#post2162069