Low Oil Pressure: Meaning, Causes, Symptoms, and Fix Guide

Various reasons can cause a sudden drop in your engine’s oil pressure. Also, driving a car running low on oil pressure can cause significant and expensive damages and should always be avoided. It’s, therefore, essential to be vigilant at all times. To help you with that, here are the major symptoms of low engine oil pressure, the most common causes, and what you can do to fix it.

How The Engine Oil System Works

A car engine is made of moving metal parts, rubbing against each other at high speed. A pressurized oil film provides lubrication to the engine components to prevent wear and tear of contact surfaces. This pressure is generated by an oil pump driven by the engine. In addition to the lubrication function, the oil circuit allows:

• The engine to cool down through a heat exchange with the hottest parts;
• Protection of the metal parts of the engine from corrosion;
• Cleaning the engine of foreign bodies (metal particles, gaskets and joints residues, etc.).

Since the oil pressure varies from 14 psi to 75 psi at high speed, it is necessary to continually monitor the minimum pressure value and continuously stay within the threshold. If this minimum value is not reached, a pressure sensor, also known as a “pressure switch” or “oil pressure sensor,” electrically supplies the low oil pressure warning light to the instrument cluster.

When there is a drop in oil pressure, an insufficient amount of oil may not reach the engine’s top and no longer fulfill its role of lubricating correctly, causing the seizure of different components.

Several phenomena can cause oil pressure drops, but they will cause extreme wear of the engine in a short time in every case. That’s why it is said that when the low oil pressure light appears on your dashboard, it is often already too late.

How To Test Oil Pressure?

To check the engine oil pressure, a tool is used to measure the system’s hydraulic pressure while the engine is running. Professional oil pressure gauges come in a kit including:

• A pressure gauge usually ranging from 0 to 140 psi;
• A flexible hose with a fitting;
• Various adapters for different car brands and models.

To measure the oil pressure in the system:

1. Connect the pressure gauge instead of the oil pressure sensor, usually located on the oil filter adapter or the engine block.
2. Start the engine, let the engine warm-up for at least 15 min or until it reaches its average operating temperature.
3. Keep the engine running over 2000 rpm and note down the pressure on the gauge. If it’s not within the normal values, more troubleshooting will be needed.

What Should Engine Oil Pressure Be?

In a normal situation, the pressure should be around 40 psi when the engine is running at 1000 rpm, and about 60 psi when it runs at 4000 rpm. Note that the recommended pressure can vary significantly from one vehicle to another. Some cars come equipped with a dry-sump lubrication system operating at a higher pressure rather than standard oil systems. Before prematurely jumping to conclusions, it is highly recommended to check the oil specifications by looking in your vehicle’s repair manual.

What Does Low Oil Pressure Mean?

A low-pressure condition happens when the oil pressure fails to reach the minimum recommended value at start-up or when the value stays below the average operating pressure threshold for an extended period. A low-pressure state is not to be mixed up with an incorrect oil level, which will, in turn, cause the same symptoms and consequences. 

Low Oil Pressure Symptoms

Low-pressure Oil Light On

The engine oil pressure warning light is a vital safety component for your vehicle. It is designed to let you know whenever the pressure reaches a dangerously low level to prevent any damage to your engine. It was also one of the first control lights installed in automobiles.

Manufacturers often use a red oil burette icon to represent the oil pressure warning light. Some newer cars will still indicate “low oil pressure” in the information display on the dashboard. No matter what icon is used, if it comes on, it means the situation is critical. It is better to stop the engine as soon and as safely as possible.

Indeed, at this stage, the oil can no longer appropriately lubricate the various metal components inside the engine. Ignoring this warning sign can lead to premature deterioration of essential parts or even a severe breakdown.

Blinking Oil Level Light

In some cases, the oil level indicator may start blinking instead of being lit continuously. The first thing to suspect in this situation is either a slightly low oil level or poor electrical contact.

When the level is only slightly lower than the minimum required to trigger the warning light, it is common to see the blinking following the bumps on the road or turning the steering wheel.

Moreover, poor electrical contact to the sensor connector or exposed wire coming into contact with the car’s body may also cause the oil pressure dial to malfunction or the indicator to blink by mistake.

Noisy Engine

When the oil pressure is insufficient, the lack of lubrication causes more friction between the engine’s internal parts. It’s not uncommon to hear a clearer friction noise than usual. Hydraulic lifters can also start to produce a distinctive rattle noise.

Most Common Low Oil Pressure Causes

In general, a drop in the engine oil pressure is due to the malfunction of one or more elements. A problem with the pressure sensor can cause it. Failure of this device often leads to engine oil leakage leading to even more significant issues.

Insufficient oil pressure can also cause irreversible damage to the oil pump, which must be under constant pressure to function correctly. An oil pump that runs dry for an extended period will probably never work as well as it used to and will often need replacing.

The use of an incorrect engine oil type or grade, a leaky oil filter, an improper oil level, a leaking engine oil cooler, or a clogged strainer can all also cause a low oil pressure condition on your vehicle. But before going any further, let’s see all of these causes in more detail.

Faulty Oil Pressure Sensor

Whenever the low oil pressure warning light comes on, the first thing to check is to ensure the sensor itself is in good working order. If the sensor is defective, it will start sending inaccurate readings to the PCM, which may cause the warning light to turn on for no apparent reason.

On specific newer car models, the oil pressure sensor’s proper operation is essential to ensure adequate lubrication of the engine’s components, considering that the PCM uses its data to adjust the oil pressure in real-time.

Faulty Oil Pump

The oil pump job is to build up the pressure and circulate the oil into the system to ensure all the engine components are correctly lubricated. The pump draws the oil in the oil pan and propels it into the engine block and the cylinder head.

When the pump starts to age, air bubbles can form inside the housing while it operates, directly reducing the oil pressure, which will light up the low-pressure warning light.

On older vehicles, the oil pump was usually operated by the timing chain, which significantly reduced the risk of failure but caused an additional load on the engine, reducing the fuel efficiency. To remedy this situation, newer car models are now equipped with electric oil pumps, effectively reducing the engine load but leaving room for potential electrical problems.

Incorrect Engine Oil Grade

When it comes to the oil grade to use in your engine, it’s super important to respect the manufacturers’ recommendation for the viscosity and oil type. Every engine is different and optimized to work best with a particular oil grade.

However, the oil may undergo premature aging. If the piston rings allow combustion residues to get into the oil pan, the fuel’s chemical components can break up the chemicals and significantly reduce its lubricating properties.

Suppose the instrument panel oil indicator does not go out as it should after start-up, immediately check the oil level and its color and viscosity. If the oil is black and runs slowly down the dipstick, an oil change may be required.

Faulty Oil Filter

The oil filter is one of the essential components of an internal combustion engine’s lubrication system. It filters dirty oil, removes dust particles, and retains metal flakes contained in the oil.

An oil filter clogged with debris can stop filtering the oil properly, allowing the particles to flow right back into the engine, gradually damaging the internal components.

Furthermore, a wholly obstructed oil filter will substantially limit the oil flow, considerably reducing the lubrication system’s efficiency. Filter replacement will be required immediately.

Defective Engine Oil Cooler

When driving under load or hauling a heavy trailer, the engine’s temperature can quickly rise and get out of hand. An external oil cooler is used on such vehicles to allow the engine cooling system to evacuate the oil’s heat.

The engine oil is transferred to the coolers using an adapter located between the engine block and the oil filter. The oil flows through the cooler while the coolant is circulating around it, absorbing the excess heat in the process.

If the vehicle is serviced as needed, the cooler should last as long as the vehicle. However, there are occasions when the oil cooler may become clogged and limit the passage of oil.

The oil filter adapter can also be the cause of the problem in some cases. Internal O-rings can sometimes leak and cause a significant pressure drop.

Finding the leak’s exact source is easier if you start cleaning the outside of the engine with a degreaser foaming spray. Protect electrical parts with plastic bags or plastic sheets and spray the degreaser around the area. Please wait for a little, wash it out with water, then start the vehicle and let it run for a few minutes. Inspect around the adapter and replace the O-ring if needed.

Engine Oil Leak

Any other leaks in the lubrication system can also create a pressure drop. The most common causes are, among others, the seals of the timing case and the front or rear seal of the crankshaft. In both cases, the leak will be greater when the engine is running. Be careful, though. The transmission usually hides the rear crankshaft oil seal, so the only visible sign of leakage is often a drop from the bottom of the transmission housing.

Even a small leak can end up causing worrying problems if the source is not corrected quickly. Over time, the oil level may slowly fall below the required minimum level and cause air bubbles in the system to induce significant engine damage.

In any case, the only remedy for a seal leaking oil is to replace it without any delay. Be sure to check that another moving part has not damaged the seal to avoid facing the same problem again in a couple of weeks. Ensure that rotating parts with which it’s in contact are smooth and free of defects before replacing the faulty seal.

Low Oil Level

Driving with a low engine oil level can create severe and expensive damages and increase the risk of ending up with a seized engine. Seizure almost means the death of your engine, as there’s not much to be done at this point. The engine will need to be opened up and inspected but, in most cases, the head will be warped, and the piston will have scratched the inside of the cylinders to the point of no return. A complete overhaul could save the engine, but the total cost may be relatively high and often beyond the vehicle’s residual value.

Clogged Oil Strainer

On older vehicles, oil pans can rust, and metal shavings can float inside the oil pan. Manufacturers install a strainer on the tube’s opening connected to the oil pump to prevent this debris from entering the oil system.

Usually, regular oil changes should prevent the accumulation of large debris inside the oil pan but sometimes, it’s simply not enough. Dust or sand may have been able to enter the valve cover and is causing the camshaft to scratch against the head, producing small metal flakes, or maybe carbon deposits found on the inside of the combustion chamber fell into the oil pan. Whatever the case is, debris found in the pan could clog the strainer, reducing the system’s oil pressure.

When something like that happens, remove the oil pan and remove the debris and metal shavings using a vacuum cleaner. Do not use a blowgun or you risk pushing small metal fragments into the oil pump. Unclogging an oil pump is a lot more complicated than simply removing an oil pan and often requires the front cover and timing belt/chain to be removed.

How Serious Is The Problem?

Low oil pressure problems are not to be overlooked. The oil in your engine is the same thing as the blood in your body. If it’s dirty or contaminated, if the pressure is not high enough or your arteries are clogged, you won’t live for long, and it’s the same with your engine. The oil system is one of the most vital in your vehicle and should be treated accordingly. Neglecting the regular maintenance of the lubrication system will directly negatively impact your car’s lifespan and its resale value.  

The Bottomline

No matter the original cause, drivers should react promptly to the first symptoms of low oil pressure. Most of the time, replacing the defective component will solve the problem right away. When in doubt, it’s always best to contact a certified automotive technician or bring your car to the nearest auto repair shop. Keep in mind that ignoring an illness’s symptoms does not make it disappear; on the contrary, it often makes things worse. The same goes for your vehicle. Regular maintenance and a mechanic you can trust will always be your best asset for keeping your car healthy and reliable for as long as possible.

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