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Blog Car Issues & Diagnoses Top 8 Reasons Why Your Car Might be Leaking Oil

Top 8 Reasons Why Your Car Might be Leaking Oil

January 10, 2020

On an ordinary day, as you’re leaving for work, you stop and notice – a pool of oil under your car. Even if it’s just a few drops, finding oil leaks under your car is unnerving. Plus, messy leaks can make your driveway look terrible.

So, what’s a responsible car owner to do? Get the leak fixed, of course. A professional mechanic will be able to pinpoint the leak for you. But in the meantime, we’ll give you a few ideas about why your car might be leaking oil – and where it might be leaking oil from.

Common reasons why your car might be leaking oil

We’re going to get into the common reasons why your car might be leaking oil shortly. But first, a quick disclaimer: There are countless different types of cars on the road, all of which can develop leaks from a myriad of locations. As such, this list is not comprehensive – it simply covers some of the most common leaks.

Engine oil leaks are usually the result of a bad seal or gasket, though they can be due to damaged parts, such as a cracked oil pan, as well. If you find your car leaking engine oil, the source may be one or more of the following:

1. Oil pan gasket

One of the most common locations for an oil leak is the oil pan gasket. As its name implies, the oil pan gasket provides a seal between the oil pan and engine block.

2. Valve cover gasket

On top of your engine, you’ll find a valve cover protecting the components inside the cylinder head. As you probably guessed, a gasket provides a seal between the cylinder head and valve cover. It’s worth noting that Inline engines have only one valve cover (and valve cover gasket), whereas V-style engines have two.

3. Front and rear crankshaft seals

The crankshaft is an internal engine component that protrudes slightly from both ends of the engine. By sticking out a bit, it can act as a mounting point for the external harmonic balancer and flywheel or flexplate. Seals, which prevent oil from leaking from the engine, sit at both ends of the crankshaft. Often, these are referred to as the front and rear main seals.

4. Oil filter and oil drain plug

Every time you get your oil changed, the oil drain plug is removed then reinstalled. The oil filter is also replaced at the same time. Needless to say, because these components are tampered with so often, they are frequently the source of leaks.

5. Timing cover gasket or seal

Although some engines have a timing belt, most modern applications use a timing chain. The timing chain is lubricated with oil and a timing cover protects the timing chain. The timing cover gasket or seal keeps oil where it’s supposed to be: inside the timing cover.

6. Camshaft seals

Camshaft seal leaks are common on engines that use a timing belt to keep the camshaft and crankshaft in sync. Much like the crankshaft, your car’s camshafts are on the inside of the engine. Overhead camshaft engines have two (or more) camshafts, both of which stick out a bit to provide a mounting point for the timing gears or sprockets. A camshaft seal fits around the end of each camshaft and prevents oil from leaking out of the engine.

7. Cylinder head gasket

Head gaskets are more commonly known for causing internal leaks, which can result in issues such as coolant consumption and coolant-oil intermix. But head gaskets can leak both engine oil and coolant externally, as well. Flat engines – also known as boxer engines – are particularly susceptible to this problem (we’re looking at you, Subaru).

8. Oil filter adapter housing gasket or seal

Your car’s oil filter screws onto an adapter housing. And guess what? That housing usually has a gasket or seal behind it that can develop leaks. If your car has a cartridge-style oil filter, leaks may also stem from the oil filter housing cap or its seal.

But wait – the leak could be something other than engine oil 

Just because it looks like engine oil, doesn’t mean it is engine oil. Your car has a lot of fluids and it can be hard to tell them apart – especially once they’ve hit the ground.

For example, your car has transmission fluid, brake fluid, and coolant. Many vehicles also have power steering fluid, differential fluid, and transferase fluid. And all of those fluids have the potential to leak, due to worn out or broken parts.

Why are we telling you this? Because you don’t want to jump to conclusions when your car has a leak. Visit a professional right away so that they can diagnose and repair the leak for you. Fixing the problem will help keep your car healthy and happy. Also, you won’t have to hide your oil-stained driveway from the neighbors anymore.