Sounds like a typical EX500 - if you uncover the pickup and allow enough time for the oil to drain from the pump, it loses its prime. Like; if your Wife drops the bike and waits for Hubby to come home to pick it up - or you change the oil and get interrupted and have to finish-up several hours later. Had both happen to the same bike.
You can repeatedly start and stop the bike, hope it will "catch".
Or, you can (carefully!) pull the filter back off, fill it full of oil, then re-install (you have GOT to be quick on the install!).
Or, you can just ignore it, and eventually the noise will quit. One way or another.
I hope you realize, "Anonymous," that the correct answer will cost you $12.
Just letting you know. "Staff" can be a real PITA.
Personally, I'm happy you didn't ask what kind of oil to use. We're not due for another oil thread until next Thursday. It comes up right after the tire thread, but before the Harley-is-going-t!ts-up-any-day-now thread.
What?....Oh, easy first check to see you have four empty oil jugs on your bench or in the garbage. Then check to see if you have oil in the sight glass. Then start the bike and see if the oil level drops. If all those check out then you probably affected the oil pressure switch wiring with you "additions" and just imagine it's noisy. Go back and undo what you did and check any fuses, then sh*tcan those lights, they look stupid anyway and ride the bike instead of screwing around with oil chages every 2k miles.
If somebody like me was doing the wiring, it's very possible that I screwed up the wiring and there's nothing wrong that putting the oil light back on it's own circuit wouldn't cure. I'm not saying that's what it is, but after some house rewiring, we had to turn on the front porch light to get the stove to light. It happens.