Rick's Free Auto Repair Advice

What to do when your oil light comes on

Honda wanring light low oil pressure

Steps to take when your oil light comes on

What does an oil light mean?

In older non-luxury cars an oil light meant only

oil light on

LOW OIL PRESSURE

one thing: you have a serious low oil pressure problem. But some older luxury cars were outfitted with an oil level sensor that alerted you when your oil level fell below a minimum level. A low oil level is a problem that must be fixed soon. A low oil pressure light is a problem that must be addressed immediately. It means PULL OVER and SHUT OFF your engine. It doesn’t mean, “KEEP DRIVING UNTIL YOU FIND A PLACE THAT SELLS OIL.”

What other oil lights are on cars?

Late model cars also have oil life monitoring lights

oil light on

Oil life monitoring system

or displays that tell you when it’s time to change oil. Some of these lights simply say “Maintenance Required” or Service Engine Soon. But don’t confuse these alerts with a low oil pressure warning light. Of all the oil related lights on your dash, the OIL light is the most serious.

What does engine oil pressure do?

Engines need a minimum amount of oil pressure

oil pressure light

Oil pressure prevents metal parts from touching

to circulate oil throughout the engine. Plus, oil pressure is what prevents the crankshaft centered between the crankshaft bearings, the camshaft centered between the camshaft bearings and keeps hydraulic lifters filled with oil to properly operate the intake and exhaust valves. Proper oil pressure is also critical to the operation of variable valve timing devices and it’s SUPER critical to the operation of high pressure fuel pumps used on gasoline direct injection engines.

What makes the oil light come on?

1) Low oil level can cause the oil light to come on

In this case, the oil pump starts sucking air, and that can cause a severe drop in pressure. The oil pressure sensor detects a drop in pressure below 7-psi. and illuminates the oil light to warn you of a dangerous condition.

2) Worn engine parts can make the oil light come on

If you’ve neglected routine oil changes and caused excessive engine wear, the clearances between rotating metal parts may be so large that the oil pump can’t maintain enough oil pressure to prevent metal to metal contact. So even though the oil pump is pumping enough oil to theoretically achieve proper oil pressure, the excessive clearances prevent the pump from reaching and maintaining the proper oil pressure.

oil light on

Worn engine bearings

3) A worn oil pump can make the oil light come on

If you’ve neglected routine oil changes and caused excessive engine wear, you’ve also caused excessive wear inside the oil pump.

4) The wrong oil filter can make the oil light come on

Oil filters are year, make, model and engine specific. If you use the wrong oil filter, it can impeded oil flow and cause the oil light to illuminate.

cut away views of oi filters

Economy oil filter with nitrile anti-drainback valve versuse a premium filter with a silicone anti-drainback valve

Even if the oil filter is specified for your engine, some filter manufacturers have been found liable for engine damage caused by using the wrong filter media. If your car or truck was running fine before you changed your oil filter and the oil light came on right after the oil change, the filter may be the cause.

5) Wrong oil viscosity can cause the oil light to come on

Oil pressure is defined as resistance to flow. One pump can pump two different liquids into the same size passage and reach two different pressures. Water, because it’s so viscous, may reach a much lower pressure than a 30-weight engine oil. So using the wrong oil viscosity can affect oil pressure and light up your oil light.

What to do when the oil light comes on?

PULL OVER and TURN OFF THE ENGINE IMMEDIATELY. I’m not kidding. Whether you’re low on oil, have a bad oil pump or a bad oil pressure sensor, the first thing to do is PREVENT engine damage by shutting off the engine. Oil starvation, even for just a minute, can cause serious and very expensive engine damage. Pulling off the shoulder and turning on your hazard lights versus driving to the next exit can mean the difference between a small service call to refill oil versus a totally seized engine costing well over $4,000.

Once you pull over, shut off the engine and

oil light on

Check oil level with the dip stick

let the engine rest for a few minutes. That’ll allow oil in the upper portion of the engine to drain down to the sump. Then remove the dip stick. Wipe it clean with a rag and reinsert it fully into the dip stick tube. Then pull it out again and read the oil level. If there’s no oil on the dip stick, you cannot drive your vehicle to buy more oil. Call a friend to bring you more oil, or a tow truck and tell them you’re stopped and the dip stick reads no oil.

oil light on

Oil must be withing the marks

I’ve seen way too many people encounter catastrophic engine failure because they tried to drive their cars to the nearest convenience store to buy oil.

Remember this:

A tow is always cheaper than a new engine.

©, 2017 Rick Muscoplat

Posted on by Rick Muscoplat


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