CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Oil light flickers when idling

The oil sensor light on my car will flicker when the car is in idle (or in park).

More info…
I especially notice this after the car has warmed up.
I just changed the oil last night, using SAE 10W-30 and the problem still happens.
The car has 87,000 miles on it (2.4 L enging)

Your first step is to confirm if this is indeed low oil pressure or a faulty oil sender.

Options: Take the car to a reputable shop and have the oil pressure checked with test gauge, or just replace the sender and see if that solves the problem.

I’m guessing at your lower RPM idling speed that your pump may not be pumping quite fast enough to keep your light from coming on. When I used to work on a farm, I’d see the oil light flicker at low engine speeds on our old tractors since the oil pump pumps faster with higher engine speed, at least in my experience.

I had an old pickup once that did that - but it was b/c the sender was leaking.

In any case, presumably you have verified that the oil level is correct. I’d next follow Scudder’s advice. I would not do this anytime soon but immediately. If the problem really is low oil pressure you can damage the engine if you let it go.

87,000 miles over how many years? What type of driving? If it’s all stop and go, the mileage can be misleading.

Follow Scudder’s advice. If it does turn out that the pressure is low at idle and the idle is correct, then the engine may be just plain tired. Oil pressure is created by the pump pushing the oil through the spaces between the parts, creating a high pressure barrier between the parts, then draining back into the pan. If the wear becomes too great, the spaces too big, the oil may flow through too readily and the pump have difficulty maintaining oil pressure. Sort of like trying to blow up a balloon with a pinhole.

A word of caution: while it’s common to blame the oil pump, it truth oil pumps are very simple interlocked impellars that spend their life bathed in oil. They really don’t wear out often. It’s generally the engine itself, particularly the main bearings and rod bearings.

Have a mechanic check the pressure with a mechanical gauge. You will then know whether the problem is the sender unit or something more serious in the engine.

I had the same problem on a 1971 Ford Maverick. The condition occured when we were on a trip. The Maverick had hydraulic lifters and they weren’t clattering at idle. I took off the oil cap when the engine was idling and could see the oil being sprayed around inside the valve cover, so I gambled that the oil pressure was o.k. and continued on the trip. When we returned home, I did have the oil pressure checked. The pressure was fine and the problem was just the switch in the sending unit.

I liked the set-up better on the cars that I owned that were made in the 1940’s and 1950’s. These cars had oil gauges that were mechanical and it seems to me that these gauges were more reliable. I didn’t care for just an oil pressure warning light that came on the later vehicles I owned.