Oil light at idle

[km2002]

Need some educated guesses (which means, no, I have no idea what to test, so suggestions regarding proper testing are way premature at this juncture; thank you very much). My wife's 93 Taurus wagon displays a flickering oil pressure light at idle. I've checked the oil level; it's good. And the engine isn't running rough at idle, either. What are the other most likely reasons this light would flicker at idle? Thanks.

[shorod]

Bad oil pressure switch. Is it also leaking oil?

-Rod

[65comet]

Oil pump worn out. Oil pickup tube gunked up. Oil filter gunked up. Putting in a super light weight oil instead of the recommended or higher weight. Those are a few more.

[km2002]

Thank you both. For the record: using the specified oil; no noticeable oil leak. We do need to change the oil. That has to wait until we get back from a weekend out of town.