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Low Oil Pressure at Idle: Possible Causes and How to Fix It!

What Is Low Oil Pressure

Most drivers probably know by now that the engine oil plays a very important role in keeping the engine at its optimum operating condition. It is the one that ensures that all of the engine’s moving parts are protected and well-lubricated. To make sure that the oil will reach all parts and corners of the engine, the pressure needs to be built up. This pressure is built up when the oil is flowing within the engine through the openings. It is for this reason why drivers tend to worry when they notice that they have a low oil pressure at idle. Low oil pressure at idle can be caused by low oil level, poor quality of oil, faulty pressure gauge, worn fuel pump, or by using the wrong type of oil.    

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Low Oil Pressure at Idle: What is Oil Pressure and Why Does it Change?


To understand what causes low oil pressure at idle, we need to know what oil pressure is and why it is important to maintain the correct oil pressure. Oil pressure involves a lot of components or elements to ensure that it is properly maintained. It involves the lubricant, the oil pump, and even the distance that it needs to travel to reach every corner and parts of the engine. 


The measure of the force pushing the oil through the oil pump and the distances it has to go through like the pipes, joints, filters and other parts that can decrease the force is known as the oil pressure. It is determined by the resistance the oil has to face when it flows through its passages within the engine.  


The oil pressure that is shown on the pressure gauge is the force needed by the pump to make the oil flow and provide the appropriate lubrication. It does not involve the pressure between system parts like the crankshaft bearings or the cams. The said gauge must show the required level which is somewhere between the maximum and the minimum to indicate that the lubrication process is correct. If the pressure level goes way below the minimum or above the maximum, it is an indication that there is a problem.  


It is important that the engine oil pressure should always be maintained at the right level to ensure that the vehicle can function properly. But why does the oil pressure change? Why does it cause a high oil pressure or a low oil pressure at idle? 


Whenever you start the engine, the oil is still cold and the pump will require more power to move it so the pressure is expected to be high. When the engine has started and the oil is already heated, making it flow easily, you will then notice a reduced oil pressure reading shown on the pressure gauge. 


To prevent wear of the moving parts of the engine upon starting, since it can sometimes take longer to heat the cold oil and make it flow easily and lubricate the metal parts,  there are multi-grade oils available on the market today that are much better than the single grade oils. 


What Causes Low Oil Pressure at idle?


Oil pressure should never go too high nor too low. You can always check it by looking at your pressure gauge or whatever oil pressure indicator your vehicle has. Older vehicles have an instrument cluster that gives an actual oil pressure indicator you can see that usually reads around 50 to 60 psi. Modern cars now have low oil pressure warning lights that illuminate whenever the oil pressure drops below 5 to 7 psi. 


You should always be aware of your oil pressure. If your vehicle has an oil pressure gauge, you should see to it that the pressure will not drop to the red zone at the bottom. If what your vehicle has is a low pressure warning light, then it should never be set off or illuminate while you are driving or when the engine is running. If you notice that you have low pressure with the gauge hitting the red zone or an illuminating warning light, pull over and stop the engine. Have it checked immediately since a low oil pressure can cause damages that can be too expensive to fix. 


Low oil pressure can be caused by a lot of things, but what causes low oil pressure at idle? Here are some of the reasons why you experience low oil pressure at idle.


  • Low oil level.


One of the causes of low oil pressure at idle is a low oil level. When the oil level in the engine is actually low, the oil pump will not have anything to work with. Aside from noticing low oil pressure at idle, a low oil level can also cause an irregular low oil pressure during high speed turns since the oil in the oil sump moves to the side, away from the oil pick up tube. 


If your oil level is low, you must investigate what caused it and correct it immediately. It can be caused by leaks, worn piston rings, excessive blowbies, or worn valve seals. To fix the low oil level issue temporarily, you can just add engine oil until you get the correct level.   


  • Poor car maintenance.


Poor car maintenance and not following the manufacturer’s recommended oil change interval can lead to dirty and contaminated oil. Old oil also tends to lose its properties and abilities such as its temperature-viscosity properties, the ability to clean the engine, or to protect it from wear and corrosion. 


A clogged up engine will be deprived of oil which can cause a serious wearing out of the engine and its components. This can be the reason why you experience low oil pressure at idle. A flashing low oil pressure warning light could also indicate that you need to have your oil changed as soon as possible. 


Whenever you decide not to change your engine oil, the old, contaminated oil can clog up the engine that can prevent the smooth movement of the pistons and the engine components. Not changing your oil regularly can lead to the development of engine sludge. Engine sludge can get stuck everywhere. It can starve the oil pump and all the moving parts of the engine that need lubrication.  


Remember that engine sludge is something you don’t want to deal with. It is a very serious problem that leads the drivers to spend hundreds of dollars on costly repairs. Engine sludge can develop when the oil starts to break down and collects on the engine. To avoid spending too much on repairs, make it a habit to change your oil regularly. 


  • Worn out oil pump.


The oil pump is the one that makes sure that the engine oil is pumped into the engine’s oil passages to ensure that the engine is always lubricated. If this oil pump fails to do its job, it won’t be able to pump enough oil needed to keep the engine lubricated as well as maintain the correct pressure. A worn out oil pump can also bleed off oil pressure in the pump that can trigger a reading of low oil pressure at idle. 


When you see the oil indicator flashing, it can be a sign that your oil pump has become faulty. You need to have it checked to get the right diagnosis and to correct the low oil pressure issue. You can fix this temporarily by using an engine oil with higher viscosity but if you want a long-term and effective solution, you will have to replace the worn out oil pump with a new one. 


  • Faulty pressure gauge. 


There are instances where a low oil pressure at idle is caused by the faulty pressure gauge, especially when you recently just had an oil change. You can have it checked and inspected to be sure. If the problem is indeed caused by a faulty pressure gauge, you will have to replace it to get rid of the low oil pressure reading.


For modern vehicles that are equipped with electrical modern gauges, you can check if it is the one causing your vehicle to give a low oil pressure warning. You can do this by testing the actual oil pressure by using an oil pressure gauge. If the reading says that you have a good oil pressure, then it could mean that you have some electrical problems that are causing incorrect meter readings or warning lights. A failing engine oil pressure sensor could be one of the potential problems that can trigger it.   


If you suspect that it is the engine oil pressure sensor that is causing the problem, you can check it using a digital multimeter while the engine is running. You can do so after you have confirmed the actual pressure using the tool. Other problems that can lead to incorrect pressure readings or warnings are short circuits and open circuits. 


  • Engine has worn out.


Since the oil pressure is made as the pump pushes oil through the oil passages and through the small spaces between the wear surfaces in the engine, when the engine becomes worn out, these spaces tend to become larger. The bearing clearance will be increased. This makes the oil flow through these spaces rather easily, making the pump no longer capable of maintaining the oil pressure at idle. 


The oil pump has impellers which the oil passes when they’re turned by the engine. Low oil pressure at idle can happen since the slower the engine turns, the slower these impellers move which means less fluid will be pumped. Insufficient fluid will be pushed in the pressurized channels when the engine is worn. 


To diagnose the problem, you can use a pressure gauge. If the oil pressure reads too low at idle, it can be an indication that the engine is suffering from wear. Using a higher-viscosity oil can fix the problem. When you are using 5W-20, you can make a switch and use 10W-30 instead. The slightly increased oil viscosity can help make up for the larger spaces and increased bearing clearance in the engine. This can help increase the oil pressure back to normal and allow the pump to maintain the correct pressure. 


  • Using oil with the wrong viscosity.


Another possible reason why you experience low oil pressure at idle is you are using the wrong type of oil. Many modern engines use multigrade engine oils since temperatures can change and can vary depending on the season. The multigrade oil is being used since it can flow thin during cold weather and become thicker when the temperature increases. It can basically maintain its proper lubricating properties throughout all seasons.  


If you use an engine oil with low viscosity during extreme cold temperatures, it can be beneficial in the cold-start lubrication but when it is used during summer, it’s another story. It can become too thin during hot temperatures that could result in low oil pressure and other problems. 


Always consult your owner’s manual to know what type of oil is best for your vehicle. In an event where the recommended blend for your vehicle is not available and some other oil is substituted, if you experience low oil pressure issues after that oil change, you need to correct it by changing it with the right oil viscosity. 


There are some vehicles that will require different summer and winter oil blends. To make sure that you don’t experience low oil pressure warnings, it is important that you do change your oil using the proper one before the season changes. 


Low oil pressure at idle can be caused by several factors. But with or without low pressure readings or warnings, you need to be mindful of your engine oil and follow the regular oil change schedule. The oil plays an important role in keeping your engine and its parts lubricated. If you notice that you have a low oil pressure, you need to check it immediately to avoid any serious problem. 

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