How to deal with a blinking check oil light

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Close-up of oil being drained from an oil pan on the underside of a car.

Check your oil regularly, lest you run afoul of the check oil light – and chew up your car's engine. (Photo Credit: CC BY-SA/Dvortygirl/Wikipedia)

Every driver should take the time to regularly check the oil in his or her vehicle. However, not only do too few car owners take it upon themselves to do this, even fewer understand how the oil circuit works. Here are some basics as to why the oil gauge may light up and why it manifests intermittently.

A common check oil scenario

Let’s say that the check oil light on your vehicle comes on when the engine revs at low revolutions per minute. Then, as the engine revs to higher rpms as you drive off, the oil light shuts off. Curiously, this can even occur when the oil level in the vehicle is sufficient. What’s going on here?

Low oil level or a weak pump

The short answer is that when the check oil light comes on, it usually isn’t an inconsequential glitch. You should pay attention. Thankfully, most newer cars are advanced enough to have oil-life monitors that can survey the state of your car’s motor oil viscosity and indicate exactly when the oil needs to be changed.

When the oil light comes on, in means that oil pressure is low. This is bad on a variety of levels. If the oil pressure is too low, it means that either there isn’t enough motor oil in the system, or the oil pump isn’t circulating enough oil to keep all the necessary bearing and friction surfaces lubricated. If the oil light happens to come on while the car is driving at higher speed, it’s even worse. You should pull off the road as quickly and safely as possible, shut off the engine and check into the problem before parts become warped or cracked.

Oil is lifeblood

When it comes to automotive engines, motor oil is the lifeblood. And the oil circuit that monitors oil level and flow is also important, but little understood. The path of the oil begins in the oil pan, where a pump sucks it up and distributes it to passages leading into the engine block. From there, the oil goes to crankshaft bearings, camshaft bearings, valve shafts and other moving metal parts that would require lubrication to help avoid excess friction and heat buildup. The detergents in modern motor oil blends help to keep filters clean, but oil changes at regular intervals are still advisable.

If your check oil light is coming on, first double-check the oil level and top it off. Check for leaks on the underside of the car, too. To be more thorough if you suspect a leak but can’t see exactly where it is, drain the oil and run a smoke test for detecting leaks. These are available at any auto parts store, or can be performed by a mechanic.

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Find the sensor

Low-rpm oil light instances generally indicate that the oil pump isn’t the problem. If the pump were the culprit, the light would also come on at high rpms. In this case, it’s probably the sensor that operates the light. This sensor has a probe that resides in one of the oil flow channels of the engine, and it uses oil pressure to close an electrical circuit. If dirt or foreign matter gets into the probe, the sensor can send a false positive to the oil light indicator.

Fortunately, the sensor is easy to replace, if you can reach it. Unhook associated wiring, loosen the sensor with a wrench and follow instructions that come with the replacement sensor for installation. Once this is done, take the car for a test drive and attempt to recreate the oil light scenario. If the light still comes on, the pump is likely broken.

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