My oil pressure idiot light is flickering, and, being an idiot, I took the cue to check oil. Sure enough, down a little. I added until oil was at the upper end of the checkering on the stick, but the light still flickers.

What's up with that?

not unusual for a highmilage engine to flicker at idle, I use20/50 sae in highmilage engines and this helps.

I had an oil pressure sender failure on my `93 245 this past winter. I replaced the sender and have had no problems since. The only other time the light flickered while driving was when I made the mistake of using 5w30 motor oil(...not by choice, the oil was free). Even then, the light only came on during deceleration.

replace the switch and cross your fingers. if it's still flickers, then have someone do an oil pressure test with a mechanical gauge. if the pressure's ok, then maybe the black wire is broken someplace and grounding out. if you said 81 to 88, i'd bet on it. a 93? be a suprise. good luck, chuck.

The problem is likely in the oil pump. It needs new o-rings or maybe a new pump. The replacement parts are pretty cheap, though there is a bit of labor involved in getting the pan out with the engine in the car.
Not the end of the world though- $200 and it should be healthy again.
Fix it soon- the oil light goes on when pressure is low enough to cause damage to the engine.
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Rob Bareiss, New London CT ::: '87 244DL/M47- 229K, 88 744GLE- 218K, 82 245T-181K Also responsible for the care and feeding of: 88 745GLE, 231K, 87 244DL, 239K, 88 245DL, 246K

When does it flicker? At idle? Or all the time?

My 93 flickered on at idling ever since new. It went back to the dealers many times, but they never fixed it. After 300,000 miles I decided to have a look at the oil pump. The O-rings were hardened and coming unseated, but having got it all apart I replaced them and fitted a new pump. Oil pressure, as measured on a proper gauge, is now back up to specification.
I posted a few months ago on how to get the pump off and on without having to drop the cross member. It can be done - post if you want details of my method.