How to Fix Low Oil Pressure

If the heart of an automobile is the engine, then the heart of the engine is the oil pump, pumping engine oil to lubricate moving parts, remove waste heat, and drive hydraulics. On many older vehicles, an oil pressure gauge in the instrument cluster gave a visual indication of actual oil pressure, usually topping out at 50 to 60 psi. Most modern vehicles, though, have done away with the oil pressure gauge, replacing it with a simple low oil pressure warning light, which illuminates when oil pressure drops below 5 to 7 psi.

Generally-speaking, if your vehicle is equipped with an oil pressure gauge, it should never dip into the red zone at the bottom of the gauge. In case your vehicle is only equipped with a warning light, then it should never come on while the engine is running. If the gauge drops into the red or the warning light stays on, stop driving immediately and shut the engine down. Insufficient oil pressure will quickly lead to expensive engine damage.

Oil pressure depends on several critical factors, such as oil supply, oil type, engine condition, oil pump condition, and the weather, to name a few. Here are a few possible causes of low oil pressure and how to fix them.

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Oil Supply Problems

Logically, if there is not enough oil getting to the oil pump, then the oil pump won’t be able to generate enough pressure in the engine lubrication system.

• If the oil level is low, the oil pump won’t have anything to work with. Low oil level might also manifest itself as intermittent low oil pressure in high-speed turns, as oil in the sump sloshes to the side and away from the oil pickup tube. Simply adding engine oil might temporarily fix the oil pressure problem, though you’ll still need to address the cause, such as burning oil or oil leaks. Burning oil is caused by worn piston rings, worn valve guides or valve seals, turbocharger leaks, or excessive blow-by. Fixing oil leaks or oil burning might involve serious engine repairs or could be something as simple as replacing the drain plug gasket.
• Engine sludge gets stuck everywhere, and can easily gunk up the pickup tube screen, starving the oil pump and the rest of your engine. Engine sludge is caused by lack of maintenance, but last-minute maintenance might not be enough to solve the problem. The engine will likely need to be disassembled and cleaned.
• A faulty or plugged oil filter could restrict flow of oil to the oil pump. If all else seems well, replacing the oil filter might solve this problem.

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Wrong Oil Viscosity

Most modern engines run multi-viscosity engine oils, most of them in all seasons. In northern climes, seasonal temperatures can swing over 100 °F, from Summer highs, over 90 °F, to Winter lows, below -10 °F. Multi-viscosity oils flow thin in cold weather, but thicken as temperatures increase, maintaining proper lubricant properties. Using a low-viscosity oil in Winter improves cold-start lubrication but would be too thin at Summer hot-engine running conditions, leading to low oil pressure and possible engine damage.

• At the next oil change, it’s quite possible that the recommended blend isn’t available, at which point some other oil may be substituted. If you’re experiencing low oil pressure problems after an oil change or seasonal change, an oil change with the correct oil viscosity might remedy the situation.
• Some vehicles may specify different Summer and Winter oil blends. Be sure to complete any oil change services with the proper oil before the season changes.

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Electrical Problems

While many older oil pressure gauges were actual hydromechanical gauges, warning lights and most modern gauges are electrical or electronic. When investigating low oil pressure problems, the best way to test actual oil pressure is with an oil pressure gauge, which you might be able to rent from an auto parts store. If actual oil pressure is good, electrical problems could cause erroneous warning lights or meter readings.

• Faulty oil pressure sensors, also called pressure switches or sending unit, are common failure points, constantly under pressure in a hot environment. Following the repair manual for your vehicle, use a DMM (digital multimeter) to check the sensor when the engine is running after verifying actual pressure with the tool.
• Short circuits and open circuits can also lead to erroneous pressure warnings. Use a DMM and repair manual to trace the appropriate circuits for repair.

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Engine Problems

When the engine is new and oil clearances are their tightest, as low as 0.002 inches, oil pressure will be at its highest, because that restriction determines oil flow and oil pressure, all else being equal. As the engine racks up the miles, bearing clearance, particularly at the back of the engine, opposite the oil pump, tends to increase. The increased bearing clearance allows oil to flow faster, lowering pressure in the entire system. Similarly, wear in the oil pump might bleed off pressure before it gets into the system.

• One way to fix oil pressure in this case is to use a higher-viscosity oil, such as switching from 5W-20 to 10W-30. This slight change in oil viscosity can make up for the increased bearing clearance, increasing oil pressure back to normal.
• The best way to fix this kind of oil pressure problem, though, is to repair the bearings. During an engine rebuild, thicker bearings will reduce clearance, restoring oil pressure.
• Oil pump wear can bleed off oil pressure in the pump. A higher-viscosity oil may resolve this problem, but a new oil pump is a better solution.
• A broken oil pump shaft or oil pump drive belt may be harder to identify, requiring some disassembly. The only way to fix this is to replace the broken parts.

No matter the mileage of the car you’re driving, it’s a good idea to pay attention to its life-blood, the correct viscosity at the correct level, adjusting for engine wear and seasonal changes. If the oil pressure warning light comes on, stop and check everything over before lack of lubrication turns your engine into a lawn ornament.