Engine Oil Leaks: What Causes Leaks and How to Fix Them

Short of your vehicle suddenly exploding in a spectacular Hollywood-type ball of fire, there are a few common issues that cause the most stress for vehicle owners. The most common include strange noises from underneath the hood, flat tires, engines that won’t start, and then the most worrisome of all: finding oil leaks where you park your vehicle.

person holding dipstick and cloth with motor oil present

What Causes Oil Leaks?

Oil leaks can be frustrating because they don’t come from one place on a car.  Therefore, if you have an oil leak, you’re almost guaranteed a trip to a mechanic unless you know where to check. Since nearly all cars experience this, from minor leaks to slow drips that develop into major problems. Check out the following four car parts and reference them against your engine oil leak to see if you can identify the issue and prevent further damage to your vehicle.

Oil Filter

Oil filters wear out, or can be aligned improperly.  Some vehicle models have additional parts in the filtration system, at the filter, that can leak. Whether you do it yourself, or it’s done by a mechanic, the filter should be changed every time you change the oil and should be checked for proper fitting.

Oil Drain Plug

At the base of the oil pan is a drain plug, accessible from the underside of your car.  Worn out thread, misaligned threads, or a loose oil drain plug can be a common oil leak cause.  It’s easy to spot as there would be fresh oil around the plug, and on the side of it where it drips down.

Oil Filler Cap

Oil doesn’t just drip down.  If your filler cap, covering where you put oil into the engine, is missing, loose or broken then the pressure of the engine could cause oil to spill out when the vehicle is running.

Valve Gasket

The gasket is probably the most common cause of oil leaks, especially in older vehicles or vehicles that are used frequently & have a high number of miles.  The gasket is a seal that joins the head two metal parts of the engine, such as the between the block and the head(s) as well as the engine block and the oil pan.  Over time, and with a buildup of sludge (oil that breaks down over time due to prolonged temperature exposure), the pressure increases which can cause leaks and failures in the seal of the gaskets.

Sometimes damage to the oil pan on the underside can cause minor to severe leaks.  This occurs when running over road debris, large rocks if traveling off-road, and even accidentally hitting an animal while traveling.  Any of these can dent the oil pan and compromise the seal or oil drain plug.

How to Stop Oil Leaks

bottle of motor oil additive productRoutine oil changes can eliminate engine oil leaks and help you avoid further damage to primary engine components. Furthermore, it’s always a good idea to have your mechanic take a walk around your vehicle to spot any signs of potential leaks. But if you want to take care of engine oil leaks at home, use a vehicle storage checklist to help you focus on critical areas for maintaining your car.

If you do develop a leak in any of the above areas, you can self-service your vehicle with parts purchased at a local automotive store.  If time, experience, or a lack of tools limit what you can do at home, then the mechanic is an option.

If the leak is small, use a stop leak additive such as No Leak.  These products are safe to use on your vehicle and are effective for most leaks.  As the seals age on your vehicle, they can shrink, dry out and become brittle.  A stop leak additive softens and conditions old gaskets, causing them to swell again and prevent further leaking.  Keep in mind these additives may not work for more severe leaks.

Additives like No Leak® work for most leaks and can last for months, or years, depending on the age of the vehicle and the degree of normal wear.  It can be a temporary solution until you can replace the seals, or you can continue using the product again if a leak begins to appear.

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  • Thanks good info

  • Thanks for highlighting the causes which might be responsible for the leakage of engine oil. It should not be overlooked and leakage should be repaired immediately to ensure the smoother performance of the vehicle. Any signs which indicate that a vehicle is suffering from mechanical deformities should not be ignored. The reason behind the appearance of such a sign needs to be identified and repaired immediately to keep the vehicle in working order.

  • i have an engine isuzu 4jg2 gear type none turbo, i have oil leaks problem i already change the oil pan, oil seals, and gaskets, the by pass hose of an alternator but still having some leaks in the sections between the block and the gear cover….

  • Thanks, for educating young engineers and automatic repairers. So good maintenance of engine is best way to it’s long life.