Why is My Car Leaking Oil?

Car Leaking Oil

How to Diagnose and Fix Oil Leaks

The most common sign of a car that’s leaking oil is a visible oily puddle that collects underneath the vehicle every time it’s parked. While this may be easy to ignore, it can lead to expensive repairs if left unchecked. The good news is that you don’t have to be a trained mechanic to find out what’s wrong.

Why is Oil Important for an Engine?

Oil ensures that your engine stays lubricated. When it leaks, moving parts can experience increased friction and may eventually overheat. They could also be forced to work harder than normal, causing them to fail. While this may lead to serious damages in the long run, it’s not a cause for concern if detected early. 

Not Sure What to do with an Oil Leak?

In this post and the video below we’ll teach you how to diagnose oil leaks. We will also include a list of the symptoms that you should look out for, the most common causes of an engine oil leak, and how to fix the problem. 

How to Tell if Your Car is Leaking Oil 

1. Oily puddle under your car

As mentioned earlier, if you find a brown or dark oily liquid under your car, chances are, you’re engine is leaking oil. If the puddle is pink or red, it could be your transmission fluid. A green or orange color is a sign that it’s your coolant. Be sure to take a closer look to see what color of fluid is underneath the car. 

2. Blue smoke coming from the tailpipe

If you see blue smoke coming from the exhaust, it’s a sign that you have an engine oil leak. Oil is not supposed to find its way into the combustion process of the engine. But, when it does, it gets burnt up together with the fuel leading to the formation of blue smoke. This may be accompanied by the smell of burning oil. 

3. Oil warning light

The oil warning light comes on when there’s a decrease in oil pressure. This normally happens when you’re running low on oil. If your car isn’t burning oil, then your car must be leaking it. The best thing to do here is to first pull over and check your oil level. 

4. Overheating engine

When the level of oil drops too low, it leaves moving parts unlubricated – causing them to grind over each other. The increased friction can cause the engine to get too hot and overheat. This may be accompanied by a temperature gauge that shoots into the ‘red zone.’ If your engine is overheating from low oil, the damage is done, and topping-off or changing the oil likely will not help.

Possible causes of a car leaking oil

One of the most common causes of an oil leak is a gasket that is damaged, worn, or torn. This is normally caused by prolonged use or exposure to external elements like road debris. A damaged gasket causes oil to leak to other parts of the car and find its way to the ground. 

As such, the first step in learning how to diagnose oil leaks is to inspect areas that you’d normally find a gasket.

1. Valve cover leak 

Mechanic checking for traces of an oil leak on engine

A valve cover that has traces of oil may indicate that you have a valve cover gasket leak. You’ll need to first check the surrounding area where the valve cover is bolted to the engine block. 

This includes taking a look at the backside as well. If you see any traces of oil, it may be escaping through a gasket that is cracked, rotten, or one that has lost its seal.

To confirm that you indeed have an oil gasket leak, wash down the engine and then check for leaking oil. 

2. Oil pan gasket leak 

Mechanic checking oil pan for an oil leak

Like the gasket found on the valve cover, the one installed on the oil pan can wear out and fail to seal the oil. This results in another oil gasket leak that occurs as the fluid circulates between the oil pan and engine block. 

Image of leaking oil pan

If you’re wondering how to diagnose oil leaks here, start by checking around the oil pan. You can first wipe off the area to confirm whether the drops of oil are coming from the pan or higher up the vehicle. 

3. Oil cooler gasket leak 

Mechanic diagnosing a leaking oil cooler

Your car’s engine oil cooler helps to remove excess heat from the engine oil. It also comes with a gasket that prevents the oil from leaking out of the cooling system. If the gasket is degraded, it will not be able to seal the oil effectively. 

Image of a leaking oil cooler

A leaking oil cooler will be characterized by oil dripping from the sides and down to the engine. Be sure to check around it for traces of a brown or dark oily fluid. 

How to replace a leaking oil cooler gasket

After diagnosing your oil leaks, you’ll want to fix the problem starting from the highest point of leakage. 

The steps given below are based on a 2012 Nissan Altima that had an oil cooler gasket leak. You can also watch the process of fixing the problem on our video Oily Puddle Under Your Car, Truck or SUV? How to Diagnose Oil Leaks.  

Tools you’ll need:

1. New oil cooler gaskets

2. Motor oil

3. Breaker bar and socket 

4. Flathead screwdriver

Steps to replacing an oil cooler gasket

First step in replacing a leaky cooler gasket

Step 1. Locate the oil cooler from underneath the vehicle. 

Step 2. Clean it along with the surrounding area. 

Step 2 in replacing the gasket on leaky oil cooler

Step 3. Start by removing the connector that’s directly connected to the oil cooler. 

step 3 in leaky oil gasket replacement

Step 4. Disconnect the hoses located at the top by taking off the clamps that secure them. You can use a marker to mark the hoses by their point of connection. 

This makes it easier to remember where each hose goes when reinstalling the oil cooler. Have a bucket underneath to catch any fluids that may come out of the hoses. 

Leaky cooler gasket replacement step 4

Step 5. Use your breaker bar and socket to remove the bolts and nuts that secure the oil cooler. 

Leaky cooler gasket replacement step 6
Replacing gasket on oil cooler that's leaking oil

Step 6. Once the oil cooler is out, remove the gasket that is found between the cooler and the engine block. 

Image of oil cooler removed from vehicle

Step 7. Remove the four bolts that tighten the cooler to access the gasket. 

removing the degraded oil cooler gasket

Step 8. Clean the inside of the unit.

clean the inside of the oil cooler unit

You can scrub the area with a razor, wipe it off with a cloth, and spray parts cleaner inside the holes. 

Pry old oil cooler gasket off

Step 9. Pry off the oil cooler gasket using a flathead screwdriver.

Clean where the oil cooler gasket was.
Image of clean oil cooler

Step 10. Clean the area where the gasket was attached to as well as the other parts of the oil cooler.

new oil cooler gasket installed

Step 11. Lubricate the new gasket and install it. Make sure it’s a perfect fit. 

replace the unit on the oil cooler

Step 12. Screw the unit back in place. 

clean the area where the oil cooler goes on the car before installing

Step 13. Before you reinstall the cooler back into the car, clean the area where it’s supposed to mount. 

install new gasket on clean surface

Step 14. Install a new gasket on the clean surface. Make sure it fits perfectly and isn’t installed backward. 

reinstall oil cooler

Step 15. Grab your oil cooler and reinstall it. Confirm that you have screwed all the bolts in place and torqued them to the manufacturer’s specification. 

reconnect and clamp hoses to the water cooler

Step 16. Reconnect and clamp the hoses and the connector to the cooler. 

mechanic checking oil levels

Step 17. Check the level of your oil and coolant. If you need to top up, do so. 

Step 18. Take your car for a test drive. Check underneath for any oil leaks once you’re back. 

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