Recently, within the last week or so, I’ve started getting a low engine oil pressure notification when idling. It doesn’t produce an error code that I can read off the ECU. The vehicle is over 100,000 miles and I changed the oil and filter after this started happening. I’ve seen mention of using a heavier oil on older cars running into this issue. What are some more troubleshooting steps I can take?
You should have someone connect a mechanical pressure gauge to the engine to see what actual oil pressure is.
The oil pressure switch may be bad.
Tester
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A very simple question . . .
Is the engine oil level correct when you get the low engine oil pressure warning?
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Good advice above, those are the two first steps. If both turn out to be ok, most likely the engine is wearing out. As wear increases, the bearing spaces get larger, creating a path for pressurized oil to leak back into the oil pan, preventing the oil from developing the correct pressure to lube the engine parts. Heavier oil and/or oil additives can sometimes help, but will usually cause other problems as the mileage increases. The solution then is either installing a replacement engine or a total engine rebuild.
The best way to mitigate engine wear is to change the oil and filter frequently, using the correct oil and filter for the vehicle. I own a 50 year old Ford truck with 200k+ miles, oil pressure measures same as new. I change oil & filter every 5,000 miles, always using 10W30 Pennzoil dinosaur (ordinary non-synthetic) oil , and a Motorcraft oil filter.
If you have a 5.4 this shows how you can test oil pressure…
It’s not always the engine wearing out. It could be a problem with the oil pump or oil pick up. Have it checked immediately before the problem actually does end up wearing out the the engine.
100k is young if oil changes have been not extended. The only time I have had the light come on it was due to a faulty oil pressure sender. Pretty cheap but yeah check actual pressure. My first new car that I had ordered the gauge package with included an oil pressure gauge. I’m embarrassed now that in heavy traffic I would rev the engine a little to increase oil pressure. Low pressure at idle is normal. Way low is not normal.
For me, that warning happened on my Corolla one time, only when engine cold, at idle, and oil level was a little more than one quart low. My fault, busy w/job and not checking oil as frequently as I should. Topping off oil level immediately solved it.
Same here, twice in 55 years of driving: on a 1970s Toyota Corona and a 1984 Chevy Cavalier. In both cases I wanted to avoid hassle and expense of a trip to a mechanic, and accepted the risk that the new oil sender unit would not be the solution.
On both cars the new sender unit fixed the problem, was inexpensive, and was easy to access and install.
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As mentioned, you need to check the oil pressure with an external mechanical gauge. That is not hard to do. The point is made that one could change the oil pressure sender but that does not guarantee anything.
Oil pressure lights are turned off by lower oil pressures; say 5 to 7 pounds per square inch.
What if you change the sender and the replacement sender opens the circuit at a pound ( or 2 or 3) lower compared to the original sender? The light is out but the potential problem remains.
If the oil pressure is really that low the usual cause is worn crankshaft bearings.
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Check your coolant level. The transversely mounted 3.5L has an internal water pump that’s driven off of a timing chain, inside of the timing cover. If the water pump starts to leak, it’ll leak coolant directly into the oil pan. This could result in a thinner viscosity which could lead to lower oil pressure, particularly at idle. The only tip off would be the oil becoming brownish in color and the oil level reading above full. If you changed the oil yourself, it should be noticeable if that’s the case.
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Are you getting the oil pressure low notification on the dashboard display or are you getting the red oil light? Not sure on a Ford but GM sends this notification to the dash display when oil pressure drops below 15 psi. The oil pressure light comes on at a lower pressure than that.
Also make sure it is not the oil level light or message. Did you do your own oil change or have it done. If you had it done, you might look at the oil filter to see if it looks new. I have a general mistrust of oil change places.