Why Do Cars Leak Oil? (11 Reasons Why)

As cars have grown in size and technology, they also have grown in complexity. Unfortunately, this means that more fluid leaks can happen in our vehicles.

Just as with other liquid substances, it can seep out, causing various problems for your vehicle. Here’s how I’m going to unmask why cars frequently leak engine oils!

Why Do Cars Leak Oil?

1. Defective Oil Filter

Many people have experienced problems with their vehicles’ oil filters over time due to improper maintenance procedures or poor-quality parts used in manufacturing.

Besides that, oil filters are designed to prevent the oil from leaking, but if a filter is damaged or defective, it can allow oil to leak out of the engine.

Therefore, a substantial amount of oil could be lost through a defective filter since the oil pump continuously moves lube grease throughout the engine!

2. Damaged Vent Valve

Vent valves are located at the top of your engine block and work like a tiny door that lets air into the engine.

Moreover, if you notice a small hole in your car’s vent or air filter, or if there’s an oily buildup around it, your vent valve may have been damaged by age and tear-down.

Overall, if there are any problems with these valves, they can cause oil engine leakage!

3. Poor Turbocharger

Oil-related factors, such as oil pollution or starvation, account for more than 90% of turbocharger failures.

Furthermore, the turbocharger will leak oil if cracks form due to mechanical problems.

Additionally, be warned that the oil seals will break and that bits will fall into the intercooler when your turbo fails.

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Unfortunately, within seconds of the turbocharger starting up, oil leaks have the potential to damage the bearing systems severely!

4. Bad Timing Cover

Like many other motor parts, timing cover gaskets deteriorate over time. As the gasket ages, oil from the interior of the timing cover could begin to leak.

As a result, the timing cover itself may occasionally be worn out rather than the gasket.

Because of that, your engine belt can soon deteriorate from the oil, creating a new series of issues that could leave you stranded and harm your powertrain.

For that reason, if a leak from your timing cover becomes severe or is ignored, it could result in several problems, including significant engine damage!

5. Failing Camshaft Seal

Smoke emerging from the engine compartment is another typical sign of a damaged camshaft seal.

Meanwhile, if oil from a leaking camshaft seal comes into contact with a hot exhaust manifold or pipe, it will immediately burn up and emit smoke.

As a direct result, though it may not have an immediate or direct impact on engine performance, a faulty camshaft seal can affect reliability since any oil leakage from a car compromises the engine’s lubrication!

6. Leaking Valve Cover Gasket

Leaking Valve Cover Gasket

Once the valve cover gasket is broken, fractured, or shrinking, one of the bolts holding the surface may enable a little leak.

When this happens, the gasket may get compromised and start a leakage, resulting in unsightly problems like oil leaks, driveability concerns, and poor engine performance.

In addition, a damaged valve cover gasket can cause an engine to fail if it is not repaired by an ASE-certified mechanic promptly.

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Above all, if oil escapes from a valve cover gasket, it could burn if it comes in contact with a hot exhaust manifold!

7. Insufficient Rear Main Seal

A rear main seal is a rubber or metal ring located at the bottom of the engine block. It seals the space between the oil pan and the rear main bearing cap.

Thus, because the leakage may develop quickly, rear main seal leaks are particularly hazardous. In addition, the placement makes it vulnerable to high oil pressure.

This is why, even if it may flow elsewhere, an oil leak from the main seal often drips from where the transmission attaches to the engine!

8. Malfunctioning Oil Centrifuge Cover

Oil purging is a common issue with older vehicles and can be caused by a malfunctioning oil centrifuge cover located on top of the engine block.

If it’s malfunctioning, this can cause car leaks because there won’t be enough pressure to push oil through these holes where it needs to go.

As a result, the vehicle will leak, causing a loss of lubrication in your vehicle’s engine block that could lead to costly repairs on your car’s engine assembly!

9. Unreliable Front Pump Seal

You’re likely dealing with a faulty front pump seal if you see fluid leaks dripping from the bell housing region between the engine and automatic transmission.

Along with this, a leak might deprive your transmission’s critical internal components of the fluid that cools and lubricates them.

Therefore, this car leakage can cause the transmission to become severely damaged if it runs out of fluid!

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10. Busted Intake Manifold Gasket

Coolant may start leaking from the system when the intake manifold gaskets deteriorate.

As you can see, if your intake leak is severe, your engine may need a hydro lock and become difficult to start as a result of coolant flooding your cylinder.

Consequently, while these could result from several different cooling system issues, one of them might be a busted intake valve gasket causing your cars to leak oil!

11. Inaccurate Crankcase Ventilation

Using a crankcase ventilation system, unwanted gasses in the crankcase of an internal combustion engine are expelled.

Without a doubt, when faced with increasing internal crankcase pressure, even the most perfectly sealed gaskets begin to leak.

Which is why oil leaks are one sign that can notify the driver that the crankcase ventilation filter needs to be serviced right away!

To know more, you can also read our posts on why cars burn oil, why use synthetic oil, and why there is oil in your spark plug.


It’s important to note that causing your car to leak oil is not illegal or unsafe—it just means some issues with your vehicle.

Undeniably, your car’s engine may occasionally leak oil owing to a faulty oil filter, a damaged vent valve, or a subpar turbocharger.

Overall, cars leak oil for a reason. Which is why it’s pretty important to check if it’s time for your vehicle to have its oil changed to prevent any damage in the future!

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