00 lincon navigator 5.4 oil pressure drop's low and light comes on , engine idles rough when pressure drops ,then pressure return s to normal range ,light goes out ,engine runs perfect. Is it my oil

Usually means the engine bearings are worn out, or the oil pump is weak.
As the oil gets hot, it gets thinner, which reduces pressure. When the engine is at idle speed the pump is not pumping as fast as it is at highway speed.

Clean the throttle body inside and the idle air control motor.This will help.

this means a mechanical gauge test is required to check actual pressure warm idling if low below 20 psi then the oil pressure pump relief is stuck open or engine bearing are worn

The engine produces oil pressure from the resistance(clearance ) between the bearings and crankshaft and the sending unit lets you know when there is no pressure. These switches ground the light in the dash around 5 psi. So as the engine gets warmer then the oil gets thinner with large amounts of clearance pressure drops. Test system with mechanical unit normal hot idle pressure should be 30-45 psi if low raise idle speed comes up then engine bearings are worn.

bad oil pump low oil make sure you have enough oil in your engine

Low oil pressure at idle can be caused by an engine with worn rod or main bearings due to (usually) high mileage . This however does not mean the engine is still not serviceable as long as the oil pressure is low only at idle. The pressure should at minimum get into the normal range at anything above idle speed.Not much oil pressure is really necessary at LOW speed. At low speed, as long as there is oil getting to the bearings, even at low pressure, you are OK. In a high mileage engine the oil pressure is often low at idle simply because the oil pump is turning slowly and cannot maintain higher pressure between the larger than normal crankshaft and bearing clearances. As speed increases the pump turns faster and supplies more oil and the pressure should go higher. Low pressure as long as it is only at idle is not a problem. However at higher speeds the pressure should be in the normal range. Such a worn engine can benefit from higher viscosity (thicker) oil such as 20W-50 in above freezing weather and 10W-40 in winter. That will increase idle pressure and the thicker oil film maintains a better film between the worn parts

Hi. This issue has several causes, but the oil light indicator is a strong sign of low pressure in the engine. This will cause the engine lubrication rate to drop, thus, producing a illuminated oil light, and erratic Oil pressure readings. The necessary actions are to have a manual oil pressure test ran on this engine, asap. When running a manual oil pressure test, you will discover if the true oil pressure is low, or normal. If the test proves that the oil pressure is, indeed, low, this will confirm that the Oil pump is suspect.

Now, if the true readings given during the manual oil pressure test are indicating that the pressure is normal, this will be the result of a failed sending unit(oil pressure switch). Although the oil pressure is suspect, this is not your only issue here. There seems to be a abnormal compression rate, present. This is causing the rough idle, and erratic RPMs. I recommend to administer a engine block compression test, as well. This test will discover if , indeed, there are issues within the cylinder heads, and block structure, such as a worn head gasket, cylinder wall issues, and cracked block. Normally, these issue will send signs, like white, or gray smoke out the tail pipe, or discolored oil. It will, also, promote erratic RPM ratings, and a rough idle. Have the oil pressure test, and engine block compression test ran, asap.

Once the test are administered, you will be able to isolate the actual problem areas, more accurately. Check the spark plug wire sets, and ignition assembly for faults, also.

Hi. This issue has several causes, but the oil light indicator is a strong sign of low pressure in the engine. This will cause the engine lubrication rate to drop, thus, producing a illuminated oil light, and erratic Oil pressure readings. The necessary actions are to have a manual oil pressure test ran on this engine, asap. When running a manual oil pressure test, you will discover if the true oil pressure is low, or normal. If the test proves that the oil pressure is, indeed, low, this will confirm that the Oil pump is suspect.

Now, if the true readings given during the manual oil pressure test are indicating that the pressure is normal, this will be the result of a failed sending unit(oil pressure switch). Although the oil pressure is suspect, this is not your only issue here. There seems to be a abnormal compression rate, present. This is causing the rough idle, and erratic RPMs. I recommend to administer a engine block compression test, as well. This test will discover if , indeed, there are issues within the cylinder heads, and block structure, such as a worn head gasket, cylinder wall issues, and cracked block. Normally, these issue will send signs, like white, or gray smoke out the tail pipe, or discolored oil. It will, also, promote erratic RPM ratings, and a rough idle. Have the oil pressure test, and engine block compression test ran, asap.

Once the test are administered, you will be able to isolate the actual problem areas, more accurately. Check the spark plug wire sets, and ignition assembly for faults, also...

Sounds more like the Throttle Position Sensor or another sensor is letting the engine RPM's drop too low. When the RPM's are too low, the oil pump is not pumping enough oil.

Have you checked all the vacuum pipes around the top of the engine.?
It`s not losing oil pressure, it`s just about to stall when the oil light comes on.
Listen for a hissing noise under the hood.
Vacuum leaks can cause real problems with the inlet manifold pressures.
Good luck.