98 chevy cavalier oil pressure light on at idle after car is warmed up.

Well it could be the sending unit for the gauge.
But odds are the oil pump or engine bearings are worn out.
As the engine warms up, the metal spaces expand and the oil gets thinner. The oil pressure drops some under normal conditions, but not more than 10 or 15psi. Normal idle pressure with the engine warmed up is probably 25psi.
You could check oil pressure with a mechanical gauge to make sure its not the sending unit.
Once the oil pressure starts staying below 20psi for long periods you'll start hearing noises.

At www.reliable-store.com
get complete guide on whether to repair or not, service it, and how to repair etc, along with wiring diagrams, electrical diagrams, torque specs, error codes, everything.

I had a 98' Chrysler Cirrus with 65,000 Miles and just as I was selling it, it did the same thing but didn't do the ticking...What I understood of i think was the oil pressure sensor.... so I put some Honey oil "very thick oil" in it and it didn't do it the whole time till it was gone..then I don't know what happend to it from there.

You might get lucky and have a faulty oil pressure switch.More likely though,the oil pressure is dropping at idle due to a worn engine.Replace the switch and hope for the best.If the trouble persists,you'll need to do engine work

My question is that if it was an easy fix why didn't he fix it? I would put a manual oil pressure gauge on the engine to check the oil pressure. When an oil light comes on that is not good. It may just have a bad oil pressure sending unit but I would confirm that with a manual gauge which you can buy at any parts store for pretty cheap. If you are hearing rattling noises from the engine I would suspect internal engine problems especially if you don't have good oil pressure. Is the oil up to the correct level? It may be something little but I would want to know what my oil pressure is and if it's not good I would try to take the car back and demand my money back because that car is not worth $2000 if it needs major work. Good luck.

Replace the oil pressure sending unit, located on the back of the engine.

If your oil pressure gets to low it can turn off the fuel pump. This may also have saved your engine. The ECM turns on the fuel thru the fuel pump relay for about 5 seconds. When engine is running oil pressure sender supplies the voltage to the pump. When engine shuts off check oil pressure and voltage to fuel pump.

engine oil pressure may be low remove oil pressure sending unit and install a pressure gauge check for pressure while warm if pressure is ok replace oil pressure sending unit oil pressure at idle should be between 5-15 psi at min

Could be that your Oil pump is getting clogged or may not be fuctioning properly. Isnt getting enough power while at a low idle because its clogged.... When your stopped or in your driveway with the light on put your car in neutral and set the parking break and rev the motor up to 2200 RPM's and see if the light turns off.. If i does then that is most likely your problem.

MOST COMMON ISSUE WITH THE OIL LIGHT IS THE ENGINE OIL PRESSURE SENDING UNIT, REPLACE IT, ALSO 3/4 SCALE TEMP IS NORMAL, THAT IS WHEN THE COOLING FAN KICKS ON, ABOUT 230 DEGREE'S F.