5 Causes of Oil Leaks in Car Engines

Is your car leaking oil? Fix it today with Bar’s Leaks. We’ve been doing it for over 70 years.

Hold up! If you don’t want to read this entire post and are instead interested in what products we have to repair an oil leak, here’s what we recommend.

Long story short: we offer a variety of stop leak products that can help with engine oil leaks. The best product for your specific situation depends on the type and severity of the oil leak.

To make it simple, are some our top options to consider before we dive deeper into engine oil leaks:

  1. Oil Seal Engine Oil Burning & Leak Repair (OS-1): This is our pro-grade solution, the strongest oil stop leak we make. This product is designed to stop most engine oil leaks. It works by swelling and softening rubber seals and gaskets, which helps them to form a better seal. This product can be used with conventional, high mileage, synthetic, and synthetic-blend oils. This product helps stop main seal, valve seals, timing cover seal, cam seals, crankshaft seal, oil pan, valve cover and all other oil leaks. It’s a little more expensive than other products, but it’s record speaks for itself.
  2. Bar’s Leaks Heavy Duty Rear Main Seal Repair (1040): This is the engine oil stop leak that made us the #1 brand for all oil leaks stemming from the rear main seal, timing cover, cam seal and anywhere else you’ll find troublesome oil leaks. Millions of bottles sold, and so easy anyone can do it – no technical expertise required. This product is specifically designed to repair leaks from the rear main seal, which is a common problem in older engines. It works by expanding and softening the seal, allowing it to form a better seal post-installation. This product is compatible with all types of engine oils.

Bar's Leaks most popular products to repair most oil leaks.

It’s important to follow the instructions carefully before installation. In general, you should add the product to the engine oil and then run the engine for a period of time to allow the product to circulate and work its way into the seals and gaskets. If you have any questions or concerns, consult the product label or contact Bar’s Leaks customer service for assistance.


Types of oil leaks in cars, their possible spots, reasons and their fixes

There are several types of oil leaks that can occur in cars, each with its own possible spot of origin, reasons for happening, and typical fixes. Here are some of the most common types of oil leaks you might experience:

  1. Valve Cover Gasket Leak: The valve cover gasket sits on top of the engine and seals the valve cover to the engine block. This type of leak can occur when the gasket becomes worn out or cracked, allowing oil to seep out. The oil leak is typically located at the top of the engine, and you may notice oil on top of the valve cover. The typical fix is to replace the valve cover gasket.
  2. Oil Pan Leak: The oil pan sits underneath the engine and holds the oil. The oil pan gasket seals the oil pan to the engine block. This type of leak can occur when the gasket becomes worn out or damaged, allowing oil to seep out. The oil leak is typically located at the bottom of the engine, and you may notice oil on the ground under the car. The typical fix is to replace the oil pan gasket, which, technically should be replaced with every oil change.
  3. Rear Main Seal Leak: The rear main seal sits at the back of the engine and seals the crankshaft to the engine block. This type of leak can occur when the seal becomes worn out or damaged, allowing oil to seep out. The oil leak is typically located at the back of the engine, and you may notice oil on the ground under the car towards the back. The typical fix is to replace the rear main seal, which isn’t that expensive by itself. The problem is many vehicles require the engine and/or transmission to be removed to access the rear main seal. This leads to high labor costs.
  4. Camshaft Seal Leak: The camshaft seal sits at the front of the engine and seals the camshaft to the engine block. This type of leak can occur when the seal becomes worn out or damaged, allowing oil to seep out. The oil leak is typically located at the front of the engine, and you may notice oil on the ground under the car towards the front. The typical fix is to replace the camshaft seal.
  5. Oil Filter Housing Gasket Leak: The oil filter housing is where the oil filter is attached to the engine. The oil filter housing gasket seals the housing to the engine block. This type of leak can occur when the gasket becomes worn out or damaged, allowing oil to seep out. The oil leak is typically located at the oil filter housing, and you may notice oil around the oil filter. The typical fix is to replace the oil filter housing gasket.

As a rule, the best way to prevent oil leaks is to keep up with regular maintenance, including oil changes and inspections of the engine components. If you notice any signs of an oil leak, such as oil on the ground under the car, or if you see warning lights on your dashboard, it’s important to have the problem addressed as soon as possible to prevent further damage to the engine. Generally, we can help if the oil leak is not too severe.

5 Common Causes of Engine Oil Leaks

5 common causes of car engine oil leaks.

In our experience, there are several factors that can cause oil leaks. Here are five we hear about regularly from customers:

  1. Worn Out Gaskets and Seals: Gaskets and seals are designed to keep oil from leaking out of the engine. Over time, they can become worn out or damaged, allowing oil to seep through and create leaks.
  2. Overfilled or Underfilled Oil: If the engine is overfilled or underfilled with oil, it can cause leaks. Overfilling can cause excess pressure in the engine, which can lead to leaks. Underfilling can cause the engine to run hot, which can also lead to leaks.
  3. Loose or Damaged Oil Pan: The oil pan is located at the bottom of the engine and holds the oil. If the oil pan is loose or damaged, it can cause leaks. This can happen if the car hits a bump or pothole, or if the pan is not properly tightened during maintenance.
  4. Cracked or Worn Out Engine Components: If the engine components, such as the cylinder head or engine block, become cracked or worn out, they can allow oil to leak out. This can happen due to overheating or age-related wear and tear.
  5. Poor Maintenance: Regular maintenance is important to keep the engine running smoothly and to prevent oil leaks. Neglecting maintenance, such as skipping oil changes or not replacing worn out gaskets and seals, can cause leaks to develop.

It’s important to address any oil leaks as soon as possible to prevent further damage to the engine. Regular maintenance and inspections can help prevent oil leaks from occurring in the first place.

How to Find Oil Leaks

Some of this is obvious, some isn’t. Here are some common steps you can take to find oil leaks in your car:

  1. Look for oil spots or puddles under the car: One of the most obvious signs of an oil leak is oil on the ground underneath the car. Check the ground where the car is usually parked, and look for spots or puddles of oil. This is the most common symptom.
  2. Check the oil level and condition: Check the oil level on the dipstick and note its condition. If the oil level is low or the oil looks dirty/cloudy or has metal flakes in it, this could be a sign of a leak or other engine problem.
  3. Inspect the engine: Open the hood and visually inspect the engine for any signs of oil leaks. Look for oil stains or residue on the engine block, valve covers, oil filter housing, and other engine components.
  4. Check the oil filter and drain plug: Check the oil filter and drain plug for signs of leaks. If the oil filter is loose or the drain plug is not properly tightened, it can cause leaks.
  5. Use UV dye: Another way to find oil leaks is to use UV dye. Add the dye to the engine oil, run the engine for a short time, and then use a UV light to look for the dye around the engine. The dye will show up as a bright green or yellow color under the UV light.

If you’re unable to find the source of an oil leak or if you’re not comfortable doing the inspection yourself, it’s best to take the car to a trusted mechanic or dealership for diagnosis and repair. Ignoring an oil leak can lead to serious engine damage and expensive repairs down the line.

Why Is My Car Leaking Oil When Parked?

Oil spot on ground, a telltale sign of a car oil leak.

This is the most common situation we hear about from customers. They think their cars are fine, but then they park them at home or work for several hours and notice spots on the ground. Simply put, your car may leak oil when parked for several reasons:

  1. Gravity: When the car is parked, the engine oil settles in the oil pan at the bottom of the engine. Gravity causes the oil to seep out through any cracks or gaps in the engine components and onto the ground. This is why you may notice more oil spots under your car after it has been parked for a while.
  2. Hot Engine: When the engine is hot, the oil becomes thin and less viscous. This can cause it to seep through worn-out gaskets and seals, which can result in oil leaks. When the car is parked, the engine cools down, causing the oil to thicken again. This can create a buildup of pressure in the engine, which can cause oil to leak out.
  3. Worn-out Gaskets and Seals: Over time, the gaskets and seals that keep the engine oil from leaking out can become worn out or damaged. When this happens, oil can seep through and create leaks, which are more noticeable when the car is parked.
  4. Overfilled Oil: If the engine oil is overfilled, it can cause excess pressure in the engine, which can lead to leaks. This can be more noticeable when the car is parked, as the excess pressure can push the oil out of the engine more easily.

Q: How much does it cost to fix an oil leak?

When it comes to oil, some leaks can tend to get expensive quickly.

The cost of fixing an oil leak in a car can vary widely depending on the location and severity of the leak, as well as the make and model of the car. Here are some main factors that can affect the cost of repairs:

  1. Type of Leak: Different types of oil leaks require different repair methods and parts. For example, replacing a valve cover gasket is generally less expensive than replacing a rear main seal.
  2. Labor Costs: The amount of time required to fix an oil leak can vary depending on the location and severity of the leak, as well as how easy it is to access the affected parts. Labor costs can vary depending on the mechanic or shop.
  3. Parts Costs: The cost of parts can vary depending on the make and model of the car, as well as the type of repair needed. Some parts, such as gaskets and seals, may be relatively inexpensive, while others, such as full-on engine components, may be more expensive.

In general, the cost of fixing a small leak can range from around $100 for a small oil leak to several thousand dollars for more complex repairs, such as replacing engine components. Obviously, the best way to get an accurate estimate for the cost of repairs is to have a qualified mechanic or shop inspect the car and diagnose the problem.

Uncommon Leak Situation #1: Oil Drain Plug

Oil leaks from the oil drain plug are relatively common in cars, although they are not as common as other types of oil leaks, such as those from worn-out gaskets or seals. The oil drain plug is located at the bottom of the oil pan, and it is used to drain the old oil from the engine during an oil change. Over time, the drain plug can become worn out, damaged, or improperly tightened, which can cause oil to leak out of the engine. Here are some reasons why oil leaks from the oil drain plug can occur:

  1. Stripped Threads: Over time, the threads on the drain plug or the oil pan can become worn out or stripped. This can cause the drain plug to become loose or fall out, allowing oil to leak out of the engine.
  2. Damaged Drain Plug: The drain plug can become damaged due to over-tightening or other factors, such as impact from hitting a curb or pothole. A damaged drain plug can cause oil to leak out of the engine.
  3. Improperly Tightened: If the drain plug is not tightened properly after an oil change, it can loosen and cause oil to leak out of the engine.

To prevent oil leaks from the oil drain plug, it’s important to follow proper maintenance procedures during oil changes, such as checking the condition of the drain plug and oil pan, using the correct torque specifications for the drain plug, and properly tightening the drain plug after the oil change.

Uncommon Leak Situation #2: Oil Filler Cap

An oil leak from a car’s oil filler cap can indicate several possible issues with the engine. Here are some possible reasons why an oil leak might occur from the oil filler cap:

  1. Overfilled Oil: If the engine oil is overfilled, it can cause excess pressure in the engine, which can force oil out of the filler cap. This can create an oil leak from the cap.
  2. Worn-out Oil Filler Cap: Over time, the oil filler cap can become worn out or damaged, which can cause oil to leak out. If the cap is not sealing properly, it can allow oil to seep out and create a leak.
  3. Clogged PCV Valve: The Positive Crankcase Ventilation (PCV) valve is responsible for regulating the flow of gases in the engine crankcase. If the PCV valve becomes clogged or malfunctions, it can cause pressure to build up in the engine crankcase. This can force oil out of the filler cap and create a leak.
  4. Engine Wear: If the engine is worn out or has excessive blow-by, it can cause pressure to build up in the engine crankcase. This can force oil out of the filler cap and create a leak.

An oil leak from the oil filler cap should be addressed as soon as possible to prevent further damage to the engine. It’s important to diagnose the underlying cause of the leak and take appropriate action to fix it. This may involve replacing the oil filler cap, cleaning or replacing the PCV valve, or performing more extensive repairs on the engine if necessary.

Uncommon Leak Situation #3: Leaking Oil Filter

If a car is leaking oil from the oil filter, it is likely due to one of the following reasons:

  1. Loose or Damaged Oil Filter: The oil filter can become loose over time, or it can become damaged due to impact or wear and tear. This can cause oil to leak out of the filter and create a leak.
  2. Faulty Oil Filter Gasket: The oil filter gasket is located between the filter and the engine block. Over time, the gasket can become worn out or damaged, which can cause oil to leak out of the filter.
  3. Improperly Installed Oil Filter: If the oil filter is not properly installed, it can cause oil to leak out of the filter. This can happen if the filter is not tightened enough, or if the gasket is not properly seated.
  4. Wrong Size or Type of Oil Filter: If the wrong size or type of oil filter is used, it may not fit properly or may not provide the correct level of sealing, which can cause oil to leak out of the filter.

If you notice oil leaking from the oil filter, it’s important to address the issue as soon as possible to prevent damage to the engine. The fix may be as simple as tightening the oil filter or replacing the oil filter gasket. Then again, if the filter is damaged or the wrong size/type is being used, it may need to be replaced.

Q: Do I need an oil change if my car shows signs of engine oil leaks?

If your car shows signs of an engine oil leak (such as the symptoms talked about above, or you notice oil dripping), it’s important to have the issue diagnosed and repaired as soon as possible to prevent further damage to the engine. However, whether or not you need to change the oil depends on the severity and type of the oil leak.

If the oil leak is small and not causing a significant loss of oil, it may be possible to repair the leak without changing the oil. However, if the oil leak is severe or if you have lost a significant amount of oil, it may be necessary to change the oil in addition to repairing the leak.

If the oil is contaminated with dirt, debris, or other contaminants due to the leak, it’s a good idea to change your motor oil to prevent further damage to the engine. Contaminated motor oil can cause increased wear and tear on engine components and can lead to engine failure if left unchecked.

Q: Can I still drive with an oil leak?

Whether or not it’s safe to drive your car with an oil leak depends on the severity and type of the leak. In general, we don’t recommend driving a car with an oil leak as it can lead to further damage to the engine and potentially even cause engine failure. Here are some things to consider:

  1. Severity of the Leak: If the oil leak is minor and not causing a significant loss of oil, it may be possible to drive the car a short distance to a shop. However, if the leak is severe or if you’re losing a significant amount of oil, it’s probably not safe to drive the car.
  2. Type of Oil Leak: The location and type of oil leak can also affect whether or not it’s safe to drive the car. If the oil is leaking from a critical engine component, such as the cylinder head or engine block, it’s not safe to drive the car. If the oil is leaking from a less critical component, such as a valve cover or oil pan gasket, it may be possible to drive the car a short distance until you get it fixed.
  3. Oil Level: It’s important to monitor the oil level in your car if you suspect an oil leak. If the oil level is low or continues to drop, it’s not safe to drive the car. Low oil levels can cause increased wear and tear on engine components, which can lead to engine failure.

If you suspect an oil leak in your car, it’s important to have it inspected and repaired as soon as possible to prevent further damage to the engine.

Need additional help? Contact us!

Contact Bar's Leaks with questions about how to tackle your engine oil leak.

Car engine leaks are complex, and there is no one-size-fits-all recommendation. If you are dealing with an oil leak issue and don’t know where to start, give us a call at 800-345-6572 (M-F, 8am – 5pm EDT), or drop us an email. Our customer support will be more than happy to help. They are US-based, and we never bury you in endless phone menus. Even if one of our products can’t help your situation, we’ll tell you exactly that so you can plan your next steps.

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