My OIL light stop engine light keeps coming on 2001 Volvo S60 2.4T, only at idle, 750-850 rpm, otherwise runs great! so far have replaced oil pan o rings, then found out about air being in oil. Checked, it has air in oil when hot. Am now replacing two strange looking gaskets on Oil Cooler attached to oil pan. It was leaking a little bit of oil at bottom of oil cooler after the pan gaskets changed. Should I change it out as well? So tightened it real tight and it takes it much longer for the light to come on, only does it at idle, five pounds pressure. Otherwise car runs great, light only on at idle. Am replacing gaskets on oil cooler, look like wagon wheels, will this do the trick. Where next? Oil pump? Isn't htere a recall on this model. Got it out of california a month ago.

You need to find out why you have low oil pressure. It is normal that as engine rpm's increase, the oil pressure will rise- the oil pump is moving oil faster. Even though your light goes out, you could still have critically low oil pressure. There should be sufficient pressure at idle to keep the light off. The light will come on when your oil pressure is almost nil- I believe for some it's as low as 8 psi. Normally, oil pressure at idle is specified anywhere from 15 to 40 psi. You would have to check specifications for your Expedition. To verify oil pressure, hook up a mechanical gauge at the oil pressure sending unit on the engine block. Check with a local shop.

The causes run from easy, simple to budget busting ruin. Low oil level, wrong grade oil, real old oil, oil leaks, internal oil leaks, worn oil pump, worn crankshaft bearings. It was pretty common on older very high mileage cars to have a fluttering oil light at stops and idle. It was time for a rebuild, or time to look for another car.

If the battery was disconnected during oil pan replacement then a idle relearn will be needed. drive car for awhile without using accessories (a/c) then return to idle shut car off 10 min then try again. If motor was lifted to remove oil pan check for broken vacuum hoses a large leak can keep engine from idling.

This is an oil PRESSURE issue, not oil level.
It is likely that when you stop, and the engine returns to idle, the oil pump is not creating enough pressure to push oil up to the top of the engine and lubricate the valve assembly.
I hate being the bearer of bad news, but the plastic impellers in most modern oil pumps do fail over time, especially if they've been disturbed by the work associated with an engine rebuild. Or, it could be that it is not sitting right on the pickup and feed tubes, and they are being blocked and causing pickup problems at low RPMs. The solution will involved dropping the pan to figure out what's going on with the pump.

Your oil pump is failing.... when your engine rpm drops (when stopping) the pump and engine rpm drop to idle..(light comes on). when you accelerate (rpm's increase) the pumps start working harder and the light goes off.... I am TRULY surprised the dealer(who did you see at the dealer???) did not know this,... THIS IS BASIC STUFF!! ... I mean 090 level mechanics...

Get the oil pump replaced immediately!!!!

Have a reputable garage check the oil pressure with a manual oil pressure gauge. Very well may have worn internal parts, or weak oil pump. Thats the only way to know for sure.

you must obtain an oil pressure gage you can use a inexpensive type like you would hang under your dash. remove the oil pressure sending unit from the engine, a little oil will leak out when you remove it, no big deal. install the add on gauge and see if the pressure at idle with the engine warmed up is over 20 lbs. if not you probably have bad crankshaft bearing but you would want to see what htings look like inside the oil pan.if the pressure goes up to about 60lbs when running fast. and is very low at idle the engine is probably worn out. if the oil pressure drops when it is running fast you may have a plugged oil screen.i have found paper towels and rags inside of engines.

its a high mileage engine.
all you need to do is use a thicker oil and the light will go out at idle speeds.

use a 50w sae valvoline racing oil.
plus stp oil treatment.

do that and that light is all gone.

The coolant temp sensor sends signal to the ECU and the ECU adjusts the idle RPM. When the coolant is cold, the engine requires more fuel to sustain idle with thick oil (oil gets thicker & more viscous when cold). This makes the engine to idle at faster RPM but it should settle down to 850 RPM or so after the coolant warms up. The sensor is nothing but a thermistor; a device that changes electrical resistance according to the coolant temperature.

It is a well Known problem within the 2.7 L family ...
Here is the deal Go to the dealer get a Mopar oil sending unit.
once under the vehicle look to behind oil pan about center ways and take pigtail (wire) off sensor then remove unit .
once removed if alot of sludge is there clean area very good then install new unit and inspect wire if it connection even looks bad cut wire and add new wire (MAKE SURE TO USE HEAT SHRINK TAPE OR LIQIUD ELECTRICAL TAPE TO SEAL WIRE COMPLETELY. >>>>NOT JUST ELECTRIC TAPE<<<<)
Ok now thats done plug wire back into unit .
Note: 2.7 L engines also have sludge problems and need to have engine flush and oil pan dropped clean oil pump screen and pan then start useing synthetic oil you should be able to go about 10,000 miles useing synthetic and you will have to only change filter 2 or 3 times . this should solve issue and help extend life of motor. SB