Oil Pressure 90 Buick Century

2 years ago, after an oil change at WalMart, the oil light came on. I took it back, they repeated the oil and filter change and it seemed fine. A month ago the same thing happened again. Once the car warms up, the light comes on. When I increase the RPMs, the light goes off but comes back on when I back off on the accelerator. WalMart this time said they couldn’t find a problem, it was probably the oil pump, and I should take it to a mechanic. The mechanic did a pressure check. He didn’t think it was the oil pump. He advised that it wouldn’t be worth the money to get into the engine to diagnose and repair the problem.

I’m not quite ready to give up on this car even though it has 230K miles on it. And it seems like too much of a coincidence that the oil light problem reappeared on my way home from WalMart again.

Are there any relatively simple things that I should look into before I give on this good old car.

One cheap and easy thing to try is replace the oil pressure sending unit. This is probably the most common reason for an oil light to come on at idle.


If the oil level was fine when Wal Mart changed your oil 2 years ago then Wal Mart did nothing wrong.

The mechanic did a pressure check. You did not state the results of the pressure check so how about filling in the blanks.
If the pressure was low then odds are the crankshaft bearings are worn out; a.k.a. engine overhaul needed.
If the pressure was fine then change the sending unit as Tester mentioned and don’t blame WM for problems on an 18 year old car with 230k miles.

From the sound of things it may be time to spend money on it or throw in the towel.

In idle the pressure was low, with increased RPMs, the pressure increased. The mechanic didn’t give me anything more specific.

If he checked the oil pressure with an external gauge and the pressure was low then the crankshaft and bearings are worn. That’s not unusual at 230k miles. In some severely neglected cases it happens at less than 25k miles.

Hard to give up on this car after all these years. I appreciate the feedback though.

My '71 Chevy Pickup w/350 CID engine had marginal oil pressure. I put rod bearings in it and while the oil pan was down put a new oil pump in. You wouldn’t believe how the oil pressure improved. On the other hand, my '76 Dodge Pickup (318CID) had the same oil pressure symptoms you describe and the rod bearings went not too long after that. Take these facts for what they’re worth.

If it’s not knocking yet and the only problem is the oil light flashing on, I would not give completely up on it yet.
Run a heavier grade oil and drive it to the bitter end. It could go a few more years like this, although I don’t think I would take any long trips in it.

Depending on where you live and temperatures, you might try running some straight 30W or 20W50, depending.

The car has been running fine. No knocking. No other major problems. So I’m going to replace the 10W30 with 20W50 (live in the Midwest) and see if I can get a few more miles out of it. It’s sure worth a try.

Thank You!!