Oil light comes on intermittently only when driving, not when idling. Checked oil level and it is fine. Only driveability issue possibly related is when in cruise control at speeds over 60mph when decel button is depressed then released the cruise speed becomes jumpy/goes up and down rapidly. Not sure if cruise is at all controlled by oil pressure. Could this mean oil pump is going? Is oil pump external/bolt on part or internal major dismantle job? Thanks! Ernie

1. You need to have an independent oil pressure gauge hooked up to the engine to check the oil pressures at various RPMs and to verify the 40 to zero drop. This will eliminate any issue with the pressure gauge or the sending unit.

2. The oil pressure variation can be caused by an intermittent blockage in the oil pick up or an intermittent sticking oil pressure relief valve. I would possibly suspect the latter if you are getting good pressure and it is intermittently dropping to zero and going back up again..
If you or previous owners have not maintained the engine with frequent oil changes you will get a sludge build up problem in the engine and this will be evident by just dropping the engine sump.

3. If you have had a check engine light warning then you need to have the vehicle scanned to see what fault codes have been generated by the computer. There will be some related to the intermittent loss of oil pressure but there may be others also..

4. You need to have the oil pressure problem checked out immediately. Running the engine when you constantly lose oil pressure intermittently will definitely cause engine damage due to a loss of both lubrication and oil cooling to critical components.

It's possible that when the engine is at idle RPM it may not produce enough pressure causing the oil pressure sender to activate the light. Does it do this when you just sit and idle the motor? You may also have a oil sender that may need to be replaced.

No, the issues are probably not related. If you are low on oil, you risk blowing your engine; that's why a tow was recommended. However, it's easier and cheaper to add oil... If you are getting a low oil pressure indication and you have a normal oil level, you should not run the engine until the problem is fixed (bad oil pump, blown or worn oil seal(s), etc.) Low oil level can result in low oil pressure, which damages the engine.

At this point, you may want to consider whether the vehicle is worth the cost of the repair. If it hasn't used oil before, the problem may be relatively simple - it could even be a faulty oil pressure sensor. But if it's blowing blue smoke or cylinder compression is way below specification, the engine is likely due for an overhaul or replacement.

More than likely, It might be worth giving the oil system a flush out. If the engine hasn't been properly maintained, sludge can build up in the oilways which can restrict oil flow at low pressure.

it sounds like your oil pump is a gonner and if you keep on driving your engine will be too if its not too late already. stop driving it and get your oil pump checked

Oil light will only come on when the sensor does not detect oil flow.You may have a circulation issue not allowing oil to return to oil pan quick enough to keep up on motorway. Have valve covers removed and check for build up at oil return ports in top of head(s)

The oil pump may be going out - the light indicates the pressure is below the proper level and when you step on the gas it spins faster/raises the pressure back up to an acceptable level.

This is something to get checked RIGHT AWAY, as these cars have a history of engine failure....possibly due to low oil pressure.

Check this LINK for more info.

The emissions system may be related, but get the oil pressure issue fixed 1st.

GL,
TD

First, check the oil level. Make sure the oil is at the proper level. If it's OK, then there maybe an oil pump problem or the oil pressure sending unit problem.
A Mechanic with an oil pressure gauge will be able to determine if the oil pump is working correctly at idle or the oil pressure sensor is bad.

Hi. Due to the fact that the oil level is fine, This will indicate that there may be some sludge build up in the block, or the oil pressure switch is damaged. The more serious issue will be a failing oil pump. To isolate the issue, simply, have a oil pressure test ran on this engine. If the test indicates that the true oil pressure is optimal at idle, kindly replace the oil pressure switch. Now, if the test proves that the pressure is indeed lower than factory specifications, this will confirm that the pump is damaged. Have the pump, and oil pump screen replaced, in this case.

NOTE_ I would, also, recommend to have the engine flushed asap.

I would have the catalytic converter checked, that is exactly what it sounds like