What Causes Oil To Leak?

What causes oil to leak?

Preventing oil leaks

Your vehicle’s engine relies on motor oil that is recirculated throughout the engine to keep everything running smooth. If any of the oil leaks out, it can lead to engine damage. Preventing the oil from leaking out is a variety of gaskets and seals. Simply put, gaskets are your engine’s last line of defense for preventing leaks.

If you discover oil spots in your garage or driveway, it needs to be investigated to determine if a gasket or seal has failed and is no longer doing its job. Read on to learn why gaskets and seals can develop leaks and which gaskets are most susceptible to leaking oil.

Why do gaskets leak?

Gaskets are required do their jobs inside of your engine, which is a pretty hostile place to work. Constant exposure to high temperatures, high pressures, vibrations and contact with hot fluids over a period of time will cause even the best gasket or seal to develop leaks. Except for very rare cases of catastrophic failure, gasket leaks start out as small drips that you may first notice as spots under your car. These may lead to unsightly stains that appear on your parking spot and eventually become more prevalent if not taken care of.

There is a natural tendency to dismiss the importance of small leaks of oil and put them on the list of things to fix later – but resist putting it off. Even small leaks can mean big expenses down the road if they are ignored. What starts out as a relatively easy fix can quickly turn into a major issue. Even a small leak can cause you to lose a quart of oil in no time.

Low oil levels can cause engine problems

Top 8 Reasons for an Engine Oil Leak (+ Signs, Fixes, Costs)

Engine oil is critical for lubricating and keeping the engine’s metal components free from dirt and debris.

So, if you have an engine oil leak, it’s not only messy but potentially catastrophic for your engine and personal safety.

This post will explore the top eight causes and five common signs of engine oil leaking from your car. We’ll also examine the severity, safety for driving, repair costs, common fixes, and other engine fluid leaks.

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Let’s get this rolling.

Top 8 Causes of an Engine Oil Leak

Your car’s engine comprises several critical components that can cause a severe or small oil leak.

Here’s a comprehensive list of the most common causes:

1. Broken Gaskets

Gaskets (mechanical seals) fill the space between two or more mating surfaces, preventing an oil leak.

They include:

Valve cover gasket
Cylinder head gasket
Timing cover gasket
Oil pan gasket

Over time, the valve cover gasket, cylinder head gasket, etc., undergo wear and tear due to friction, load and compression, oil pressure, and high temperatures.

Compromised gaskets could result in an engine oil (motor oil) leak.

2. Cracked or Dried-Out Seals

Like the valve cover gasket and timing cover gasket, your vehicle also comprises several oil seals, like the crankshaft and camshaft seal, that keeps engine oil from spilling.

Eventually, these seals dry out, crack, or get damaged, causing a motor oil leak.

But here’s the thing: diagnosing a crankshaft or camshaft seal leak is tricky, so it’s best to consult a professional.

3. Bad Oil Filter

A damaged or incorrectly installed oil filter can cause an engine oil leak. So, check if the oil filter is loose or displaced, especially if you’ve noticed an oil leak after a recent oil change.

Moreover, since oil filters trap contaminants, your oil filter can get blocked with debris, resulting in an engine oil leak.

Pro tip: Replace your oil filter roughly every six months or after 5,000 to 10,000 kilometers.

4. Loose or Over-tightened Oil Drain Plug

While a loose oil drain plug is a common reason for an engine oil leak, it’s only likely to happen if you’ve fastened it by hand. In such a scenario, the oil drain plug may come undone while driving, resulting in an oil leak.

In contrast, over-tightening the oil drain plug could damage the threads, eventually resulting in an oil leak.

5. Damaged Oil Pan

Since the oil pan sits underneath your vehicle, it can easily get damaged due to road debris, accidents, or hitting a speed bump.

Typically, a cracked or punctured oil pan will result in a significant leak, leaving big puddles of oil under your vehicle.

6. Excess Oil in Your Engine

Oil leaking from your car could happen due to an overflow of excess oil. It could also be due to an oil spill while getting an oil change.

When this happens, you’ll notice an oil puddle under your car, but the engine oil light on your dashboard won’t be lit up.

7. Irregular Oil Changes

Engine oil contains several additives, like a cleansing detergent, anti-rust, and friction-reducing agents. So, if you don’t change your oil regularly, it can lead to a buildup of dust and debris, resulting in the oil turning thick.

Thicker oil adds pressure to the oil gasket seal, which may weaken the seal and result in oil leaks.

Additionally, the concentration of the additives tends to decline over time, making your engine parts more susceptible to corrosion and an oil leak.

8. Driving in Extreme Conditions

Driving in extreme conditions, like high saline places or freezing temperatures, could also lead to an engine oil leak.

Why?
Salty conditions tend to corrode the metal components, resulting in more frequent engine oil leaks. And long drives or excessive acceleration in cold conditions can strain the gaskets, seals, and other engine components, reducing their durability and causing oil leakage.

Now we know what causes a car oil leak, let’s find out how we can prevent oil leaks from becoming catastrophic.

5 Common Signs of an Engine Oil Leak

Catching engine oil leak signs early can help you prevent severe engine issues and safety concerns.

Here are five common signs of your car leaking oil:

Oil puddle in your driveway: Dark brown or yellow puddles in your driveway or parking spot indicate an engine oil leak.

Engine smoking: An engine oil leak can sometimes leak oil onto the exhaust manifold, causing smoke to come out of the engine area. This occurs when the engine block is overheated due to a low transmission fluid, brake fluid, or oil level.

The smell of burning oil: When leaking oil drips onto heated engine parts, you’ll notice a thick burning oil smell from your car. You might even hear a sizzle. But note that the burning oil smell can occur for several reasons, like a faulty valve cover, broken oil filter, or engine oil pan.

Lit low engine oil light: An illuminated low engine oil light on your vehicle’s dashboard comes on when your car has low oil pressure. It could also occur when your vehicle is low on oil or has dirty oil.

Engine overheating: An engine oil leak can lead to a rapid decline in your engine oil level. Without adequate engine oil, your pistons will grind against other engine components, resulting in your engine overheating.

Next, let’s review the safety concerns an engine oil leak poses.

How Serious is an Engine Oil Leak? 3 Critical Reasons

Though engine oil isn’t highly flammable, it can still cause fire and pose other major safety threats. Let’s take a look:

1. Fire And Safety Hazard

An engine oil leak leading to fire is rare (but possible). The average engine temperature ranges between 190-220 ℉, and engine oil ignites at 300-400 ℉.

However, driving with a low engine oil level could lead to a sudden spike in engine temperature, increasing the chances of engine oil burning.

2. Engine Damage

Sometimes, a small leak could result in the engine oil level gradually dropping below the minimum mark.

If neglected, the engine’s rubber hose or seal could deteriorate prematurely due to the heat generated from the lack of lubrication or the debris accumulated. This can damage the car’s radiator and HVAC system (heating, ventilation, and cooling system) or lead to permanent engine damage.

3. Pollution

Used engine oil contains toxic agents like lead, zinc, and arsenic shaved off the engine’s metal components. If this leaked oil gets absorbed into water or sewage systems, it could contaminate our waterways.

Let’s find out if you can still drive with an oil leak.

Can I Drive With an Engine Oil Leak?

It depends on the leak’s severity.

You can drive if you have a small leak but good oil levels. However, get the leak fixed ASAP. Also, consider bringing extra oil to top up if you have to go somewhere in an emergency.

However, avoid driving if you have severe oil leakage or your oil levels are below the minimum marker. If you keep the engine running despite low engine oil levels, you could face severe engine damage or permanent failure.

Wondering how to fix an engine oil leak?
Read on to find out.

How to Fix an Engine Oil Leak?

Fixing an engine oil leak is complex. However, here are some checks you can do yourself:

Check if the oil drain plug is correctly installed. If that’s fine, inspect the vehicle’s undercarriage to determine the root cause of the engine oil leak.

You can use an additive like the oil stop leak to soften or condition a lousy rubber hose, seal, or oil cap if it’s a small leak (leaving an oil spot or two).

Should the cause of the oil leakage be something more severe or remain undetected, your best option is to get your mechanic’s help to resolve it.

Before you contact a professional, let’s ensure you’ve got a fair idea of the estimated repair costs.

How Much Does it Cost to Fix an Engine Oil Leak?

Repairing engine oil leaks ranges from $100 to $2,000, sometimes even higher, depending on the severity of the oil leak, the type of vehicle, and labor costs.

Here are the average estimated repair costs, excluding labor:

Oil cap: $8-20
Oil drain plug gasket: $30-50
New engine oil filter: $30-75
Repairing gasket damage: $80-$200
Repairing an oil pan: $100-$550

The oil stain in your driveway could be other engine fluids too.
Here’s what you need to know:

What If the Leak Isn’t Engine Oil? 4 Other Types of Fluid Leaks

Engine oil leaks aren’t the only fluid leaks you could face. Here are four others you should know about:

Brake fluid leak: A brake fluid leak could hamper your braking power or cause complete brake failure. Luckily this type of leak is easily identifiable and is mainly caused by a faulty brake line or worn-out brake pads.

Coolant or antifreeze leak: When you have a coolant leak, your car may take longer to warm up. You may also see steam coming out of the hood while driving or after you stop.

Power steering fluid leak: The consequences of a power steering fluid leak are as severe as a brake fluid leak. Moreover, you’ll notice a hissing sound under your vehicle’s hood, and your steering might feel heavier.

Transmission fluid leak: If you notice the smell of burnt oil while driving or after, you may have a transmission fluid leak. Faulty oil seals, hoses, or a head gasket could cause this leak.

Why Is My Car Leaking Oil?

Whether it's a couple of drops or a big puddle, ignoring an oil leak can quickly lead to expensive engine damage.

There are multiple reasons why cars leak oil. Losing too much oil too quickly can seriously damage your engine, so it’s vital to deal with this problem ASAP.

What Can Cause an Oil Leak?

The main reasons for oil leaks are failed engine gaskets and worn O-rings and seals that shrink and harden due to age, heat and pressure. That produces the perfect environment for an oil leak. The oil pan drain plug, oil filter or rocker (valve) cover gaskets are the most likely culprits, so let’s look at these and other possible reasons why a car might be leaking oil.

The most common cause of gasket and seal failure is lack of maintenance. Going too long between oil changes causes oil to break down, allowing old oil to become contaminated from condensation and combustion by-products. Once saturated with contaminates, acids develop in the oil. These acids attack and degrade gaskets and seals, leading to oil leaks. Always have any leak checked out by your mechanic. Repairing leaks will save you from costly repairs down the road.

Gaskets, Seals and O-rings

Gaskets and seals are designed to keep oil in your engine where it belongs, while keeping out dust, dirt and moisture that lead to oil breakdown and premature engine damage.

These gaskets and seals will leak oil if they fail. Here’s where you’ll see the leaking oil:

Rocker (valve) cover gaskets: Look for dirt and gunk buildup at the top of the engine and small puddles of oil around the cylinder head indents and spark plugs. Also check for oil spots or drip stains under the center of the engine, as well as a burning oil smell. These leaky gaskets are a common cause of an oil leak and are easy to identify and repair yourself.
Front and timing cover gasket and seal: You’ll see oil leaking from the front or center of the engine.
Front main seal, timing cover gasket or seal: When these seals or gasket fail, you’ll see oil slung all over the drive or timing belt.
Rear main oil seal: If the top of the engine is dry, you’ll see oil dripping from between the engine and transmission, and the flywheel is covered in oil. In this case, removing the transmission inspection cover is necessary to confirm the leak.
Camshaft seal: Located at the rear of the cylinder head, a bad camshaft seal will leave oily residue below the rocker cover.
An oil pan gasket: This gasket can leave drops anywhere under an engine, which means diagnosing a bad oil pan gasket can be tricky. Oil from just about any other leaking engine gasket or seal will drip over the oil pan. It’s important your mechanic verifies the leak is from the oil pan gasket and not just oil from a different source.
Oil filter adapter mounting gasket: If you see oil dripping from the oil filter area, check the filter and the filter mounting adapter gasket. Over-tightening can not only damage the oil filter gasket, it can damage the adapter gasket as well.
Head gasket; Although rare, a head gasket can cause an external oil leak and is often misdiagnosed as a rocker cover or camshaft seal leak. More likely, you’ll see white smoke coming from the tailpipe signaling coolant from a bad head gasket is burning in the combustion chamber.
Dip stick tube O-ring: A dip stick tube that is loose, wobbly or cracked can result in a significant oil leak. If your dip stick is loose, or its mounting bracket is broken or missing, make it a priority to get it repaired so that you can check your oil.

Other Causes of Oil Leaks

Oil pressure sending unit. Oil sending units can commonly cause a slow leak or, because they are screwed directly into the engine’s oil pressure system, a gusher. A telltale sign that an oil sending unit is failing will be the oil light flashing, or erroneous oil pressure readings. On newer cars, a bad sending unit can send false low oil pressure data to the engine computer, which in turn will shut off the engine for no apparent reason.
Oil pan: The oil pan can leak if road debris or driving over a curb has caused a puncture.
Oil pan drain plug: Over-tightening the oil pan drain plug or oil filter during an oil change can crush the gaskets, creating a gap for oil to leak out. Over-tightening the oil pan drain plug can also strip the threads on the drain plug. Replacing the drain plug is a simple fix, although you may need all new oil. However, if the threads inside the oil pan are stripped, then you’re looking at a costly repair.
A bad, stuck or clogged PCV valve: This can cause all kinds of headaches. One is increasing internal engine pressure, which results in the failure of one or more engine O-rings, gaskets or seals.

Poor Installations

Improper part installation: If you over-tighten and crush a gasket, or if you don’t tighten bolts tight enough or in the correct sequence, those gaskets and bolts can leak oil.
Oil filter “double gasket”: This is a common mistake that happens when replacing an oil filter. The old filter gasket sticks to the engine, and the new filter and gasket are installed on top of the old gasket. This often results in catastrophic engine oil loss.