
Normally your car’s oil pump drives enough oil through the engine to keep all the moving parts properly lubricated. If the oil pump starts to fail or components in the oil system start to clog the reduced oil pressure can lead to excess friction within the cylinders and other sensitive areas that need lubrication.
This can damage your car in a variety of ways. Not the least of which being engine overheating, a blown head gasket, a cracked cylinder head, or a cracked engine block. Just to name a few.
So, if you’ve been noticing symptoms of low oil pressure such as the engine running hot, strange rasping noises, or a burning oil smell, the wise move is to ferret out the cause before something breaks down.
What Is Considered Normal Oil Pressure at Idle?
The average oil pressure at idle for most cars range between 20 to 30 PSI. Though it can vary from one model to another and the temperature of the engine can also be a factor. Oil pressure can also be higher in trucks and cars with large engines.
If you’re not sure what your car’s oil pressure is supposed to be at idle, you can always check the owner’s manual or the repair guide for your make and model.
What Does Low Pressure at Idle Mean?

Low oil pressure at idle often means that your engine is low on oil. Usually, this is due to a previously unknown leak, or not filling your oil fully after your last oil change.
Of course, this decreased oil pressure also means that the engine isn’t getting the lubrication it needs to run efficiently. Not only can this damage multiple components, and the engine cooling system, but it can also cause the engine to gradually start to overheat.
At the same time, oil also starts to break down when overheated, causing it to lose more of its lubricating properties. You end up with a double whammy of worsening lubrication and heat buildup. If left unchecked, it can cause catastrophic damage to the engine!
Is Oil Pressure Different at Idle and High RPMs?
Oil pressure is at its lowest when the car is idling with low RPMs. This is where oil system mechanical faults tend to first show themselves.
When you start accelerating, which brings the RPMs up the oil pump moves faster to keep up with the cycle of the engine. This can sometimes mask the symptoms of things like a small oil leak or the early stages of engine sludge build-up. Only to have the symptoms of low oil pressure return again when you’re stuck idling at the lights or sitting in stop-and-go traffic.
Symptoms of Low Oil Pressure At Idle
There are a few symptoms of low oil pressure that you’ll often notice before the oil warning light comes on. This can include things like the engine feeling down on power, while also running hot, and perhaps even making ticking or rasping noises due to increased friction between the piston rings and the cylinder walls.
1. Engine Performance Problems

The excess friction and lack of lubrication from low oil pressure can severely hamper engine performance. Early only the signs might be subtle, like poor MPG. Yet as oil pressure diminishes, your engine might start suddenly losing power, stalling out while idling, or running hot.
Unfortunately, these symptoms are easy to mistake for other mechanical faults. Though it’s always wise to start any engine troubleshooting by checking your oil level. If it’s low your oil pressure problems might be related to a leak somewhere in the oil system itself.
2. The Smell of Burning Oil

A lot of low oil pressure problems are due to an oil leak, which can leave drops of smoldering oil on hot engine components like the exhaust manifold. As the leak progresses the burning oil smell will get worse and will be especially noticeable when you’re sitting idle.
The aroma is allowed to gather around the car. When you set off again, it blows away in the wind, making it easy to simply “Assume” that the burning oil smell was from someone else’s car. Though with some cars you can put the cab climate controls to “Fresh Air” without the heat or AC on, and some of the burning oil aroma might still come through, even if you’re driving down the road.
3. Strange Engine Noises

The excess friction from low oil pressure will often start out as a strange ticking or rasping noise. As the oil pressure decreases or the oil level gets lower the noises will worsen into grinding, knocking, and even clunking sounds as the pistons, rings, and cylinders start to suffer from a severe lack of adequate lubrication.
4. Engine Running Hot or Overheating

The excess friction from low oil pressure will gradually start to drive up the temperature of the engine block and the engine cooling system. Without the proper amount of oil pressure, your car’s engine will continue to get hotter and hotter, which will further degrade the lubricating properties of the remaining oil.
You might not notice the heat rising at first when you’re driving down the road, as the radiator and the outside wind might help dissipate the heat energy from the system. Especially on a cold day. Then when you’re stuck in traffic or idling at the lights, the heat from friction starts to buildup rapidly. It might even cause your car to overheat at the worst possible time.
5. The Oil Warning Light Comes On

The oil warning light coming on while you’re idling at the lights or stuck in traffic is a sure sign that the oil pressure or oil level has reached dangerous levels. There’s a reason why this gauge is red, as it’s a true emergency. Especially since a lot of automakers set the threshold for the oil warning light to come on when oil pressure is disastrously low.
Every once in a blue moon, the oil pressure warning light will come on due to an oil pressure sensor failure. Though this is the exception and not the rule.
If you check your oil level and it’s low, you absolutely have to stop the car and get it towed. If the oil level is normal, then chances are good that it’s either the sensor going out or the oil pump itself died. If you’re seeing any other signs of low oil pressure, like rasping noises, poor MPG, or the engine running hot, it’s most likely the oil pump is dead and you need to get the car towed.
If you aren’t seeing any other signs of an oil pressure problem or oil leak and the check engine light comes on as well, check the codes.
Causes Of Low Oil Pressure At Idle
The most common reasons why a car has low oil pressure at idle is either an unnoticed oil leak or a failing oil pump. Though engine sludge and/or a clogged oil filter also sit near the top of the list. Different faults might also manifest different symptoms when the car is idling that you might not easily notice when you’re driving down the road.
How to Test Oil Pressure
If you suspect that your car’s performance issues and strange noises it makes while idling are due to low oil pressure, you can test it yourself at home with a pressure tester tool and the following steps.
1. An Oil Leak Causing Low Oil

An undiagnosed oil leak is one of the most common reasons why you notice symptoms of low oil pressure at idle. If it’s something major like a front or rear main oil seal there will be copious amounts of oil pouring out. It’ll get on the exhaust manifold giving off burning oil odors and possibly even smudgy blue smoke. You’ll also notice oil dripping under the car in your driveway or your favorite parking spot at work.
Though it’s also possible that it’s a small oil leak in the pan gasket, the oil filter, or even stripped threads on the oil drain plug letting out tiny amounts of oil. As the oil level in the pan and in the system gets lower the oil pressure decreases and the symptoms of excess friction from poor lubrication increase.
How to Fix
The quick/temporary fix for low oil pressure due to an oil leak is to top the engine oil up again. As long as it isn’t a severe leak, such as a completely blown front main oil seal, you should be able to get home or to the mechanic without any severe engine damage.
Of course, you’re still going to have to find and repair the oil leak before it’s safe to drive the car again.
If it’s something simple like stripped threads on the oil drain plug or something punctured the oil filter you can probably handle the fix yourself for less than $50.
If it’s a minor leak in a front or rear main oil seal, you might be able to get away with pouring a sealant additive into the oil. Though this is another one of those times when the product over-promises a permanent fix when really, it just buys you another 3 to 6 months to save up for the proper repair.
If you have a major leak in a front or rear main oil seal, or you have the funds on hand, the wise move is to take the car to a mechanic to have the seal replaced. They can also look for other signs of oil system problems that might be contributing to your low oil pressure at idle.
The part cost for a front or rear main oil seal is usually less than $100, with some being only $20.
Front main oil seals tend to incur fewer labor costs, and you might only have to suffer a labor charge of $150 to $200 to have a mechanic replace them.
Replacing a rear main oil seal tends to be more labor-intensive, and you can expect a mechanic to tack an extra $225 to $350 or more to a final repair bill of around $450.
2. Oil Sludge Buildup

Oil sludge that builds up from having gone too long between oil changes can also cause oil pressure to be low when idling or driving along at low RPMs. This is essentially oil that has started to gum up throughout the oil system. When it accumulates in the oil pickup pipe sufficient oil can’t be delivered at the correct PSI to the rest of the engine.
Yet when you check your oil on the dipstick it reads as being normal, which usually ruled out an oil leak. Though if you look closely at the oil, perhaps after wiping it on a white piece of paper or a clean shop rag, you might see particles and gunk suspended in the oil.
How to Fix Oil Sludge Build Up
If you catch it early, you might be able to fix the oil sludge by flushing the oil with a sludge remover and the following steps.
Step One: Perform an Engine Flush with a Sludge Remover
Pour a high-quality oil sludge into the engine oil just like you would if you were adding oil. Then start the engine and let it idle for a good 10 to 15 minutes.
The sludge remover detergent will circulate through the oil system, breaking up sludge deposits and suspending them in the existing oil. Then drain the oil to pull the majority of the loosened sludge out of the system.
Step Two: Perform a High-Quality Oil Change
A high-quality oil change with a full synthetic or synthetic blend with high viscosity and cleaning additives included will help clear lingering sludge deposits. It also ensures that your engine will run as smoothly as possible.
Step Three: Add an Oil Treatment
During the oil change, make sure to add some oil treatment that’s formulated to help engines run clean. Ideally, you want to use one that’s meant to stay in the oil throughout the life of the oil change.
Step Four: Drive the Car
Drive the car for another 500 to 1,000 miles or whatever the oil treatment recommends.
Step Five: Perform an Another High-Quality Oil Change
Drain the oil to clear out any lingering oil sludge deposits. Then give the car another high-quality oil change. This will give you the cleanest slate possible.
If your engine sludge problem is severe, then you might need to take it to a mechanic to have a manual cleaning performed. This is usually beyond what a capable DIY mechanic can handle.
The mechanic will likely need to clean the valve covers, the oil pan, and cleaning the pickup pipe, which can run you anywhere from $250 to $500 in mechanic labor costs.
You also shouldn’t be surprised if the mechanic recommended replacing the oil pump. This might seem like they’re piling on, but in the case of severe sludge oil problems on a high-mileage engine, it’s probably a wise move. Especially since they’ll already be working with the oil system, meaning the added labor cost won’t be that much.
3. A Failing Oil Pump
If your car’s oil pump is going out due to age or oil sludge buildup, your oil pressure will drop dramatically when the engine’s idling. This is because the oil pump moves in time with the cycle of the engine. Thus, faults in the oil pump tend to show up when it’s at its lowest power/pressure level. When you start accelerating the oil pressure picks up and more lubricant stays in the oil system, hiding the symptoms at first.
How to Fix a Failing Oil Pump
Replacing a failing or bad oil pump is usually not something that a DIY mechanic can handle on their own. A mechanic usually has to install the oil pump, and they can also run diagnostics on the rest of the oil system to ensure it’s working correctly. If oil sludge was an underlying reason why the oil pump failed they can also perform a purge and manual cleaning during the oil pump replacement process.
The part cost for a new oil pump can range from as little as $75 to as much as $450. Though the real-world average is right around $250.
You can expect a mechanic to tack another $150 to $250 in labor costs to a final bill averaging around $375 to $500.
4. Wrong Viscosity of Oil

If you recently did your own oil change and used an oil with a different viscosity it won’t be able to move through the system properly, which can cause low oil pressure or even overly high oil pressure. The symptoms just show up easier at idle when oil pressure is naturally at its lowest.
Automakers make very specific recommendations about the type of oil and viscosity that should be used in all of their engines. This is based on hard science and the engineering specs of the engine, oil pump, and various moving components. Deviating away from the correct viscosity of oil can affect the oil pressure and lubrication with disastrous consequences.
How to Fix the Wrong Viscosity Oil
If you catch it early, you should be able to simply drain the oil and change it with the correct oil with the viscosity rated for your engine. The wise move here is to go with the highest quality oil that the automaker recommends in the owner’s manual. This is usually a full synthetic or synthetic blend with the same viscosity and special additives.
If you’ve been running your engine with the wrong viscosity of oil for a long time, and you’re hearing all kinds of strange rasping, ticking, or grinding noises, along with the common symptoms of low oil pressure at idle, the wisest move is to bring the car to a mechanic. They’ll need to perform a thorough engine inspection. Depending on the type of oil you used, you might have a severe oil sludge problem that requires cleaning.
5. A Clogged Oil Filter

A clogged oil filter or one that’s gone too long without being replaced on schedule can make it hard for the oil pump to pick up a sufficient volume of oil for the cycle of the engine, causing low oil pressure. Sometimes this is a matter of going too long between oil changes and oil sludge starts clogging up the filter. Though the real worry here is that something is causing your oil to be contaminated by particulate matter.
When you check your oil, wipe a little on a white piece of paper and look for tiny particles suspended in it. This might be due to the oil cap being loose in the engine bay or unfiltered air entering the engine from a loose/missing air filter. Though flecks of metal in the oil could also be a sign that engine wear due to poor lubrication is occurring inside the engine’s moving components.
How to Fix a Clogged Oil Filter

The quick fix for a clogged oil filter that’s causing low oil pressure is to have a complete oil change performed with a fresh oil filter replacement. This should get the oil flowing smoothly to the oil pump and will take the current load of particulate contamination out of the oil system.
If your clogged oil filter was due to contaminated oil, you’ll need to determine the source and correct it as well. This usually starts with replacing the air filter for good measure and checking to make sure that all caps, ports, and dipstick tube is closed properly.
If you saw metal flakes in the oil, the wise move is to have a mechanic inspect the engine and oil system to determine what other problems might be going on.
Frequently Asked Questions
How Accurate Is the Dash Oil Pressure Gauge?
The oil pressure gauge displayed on most dashboard instrument clusters is directly tied to an oil pressure sensor that’s installed in one of the primary oil ways of the oil system. They’re usually installed between the oil filter or oil pump and the engine block. This gives you a vague reading of the oil pressure but isn’t 100% reliable.
If you see your oil pressure gauge start to suddenly drop, you can trust that there’s a fault in the oil system and you need to pull over as soon as possible to troubleshoot it. However, the sensor location can be receiving oil pressure, while other parts of the oil system are not. It can also be gummed up by oil sludge, which can further give a false reading.
So, you shouldn’t trust a dash oil gauge that looks normal, even if you’re noticing signs of low oil pressure.
Conclusion
Oil systems faults tend to reveal themselves early on when the engine is idling, and oil pressure is at its lowest.
Many times, the rasping or ticking noises, poor engine performance, and hot running engine with low oil pressure at idle can be directly attributed to low engine oil. Topping up the engine oil will usually get you home again. Though it also means there’s a leak somewhere that needs to be fixed before the car is truly safe to drive again.
If your oil level looks normal, then chances are your low oil pressure when idling is due to a mechanical fault such as a dying oil pump. In a scenario like this,a pressure test will return a number below 20 PSI, telling you that the pump is failing and needs to be replaced before the lack of proper lubrication causes engine damage.
If you are long overdue for an oil change, a clogged oil filter and/or oil sludge are likely preventing the oil pump from building up the proper pressure it should at idle. If you catch it early, you might be able to simply have an oil change performed. Though if it’s gone for a long time like that, the oil pump might also be compromised, or severe sludge might need a mechanic to physically clear it away.

Written By
Jason Farrell
Jason Farrell is a certified master technician, the editor of Mechanic’s Diary in Pittsburgh, Pennsylvania. He is ASE (Automotive Service Excellence) certified and earned a Bachelor’s Degree in Automotive Technology from Pittsburg State University. With nearly 18 prior years of experience in the automotive field, he has extensive knowledge about Domestic, European, and other foreign makes and models of cars and light trucks. Jason’s experience working as a technician and service manager at dealerships, gave him the experience and know-how of most aspects of inspection, diagnosis, and repair from engine and drivability to electrical, HVAC, brakes, steering and suspension and everything in between.