Common Causes of Car Oil Leaks

What To Do If You Find an Oil Leak

Any signs of liquid found at the underside of the car should be investigated immediately to ascertain exactly what the liquid is and where it is coming from. A small leak can over time grow into a large and costly problem.

It is important to make sure the leak is definitely coming from your car and not from another vehicle or a puddle on the street.

To determine what the liquid is, simply slide some white cardboard underneath the car whilst it is parked to collect a sample from the leak. Oil is easily identifiable by its colour and texture – it is typically a shiny brown or black and feels slick. Other types of liquids which may be found in a leak have a distinctively different appearance to oil – these include, coolant, water, transmission fluid, brake fluid and steering fluid.

common causes of car oil leaks

Why Is My Car Leaking Oil?

Problems With the Oil Filter

Sometimes the oil filter may be loose or not properly aligned – this can cause leaks. During every annual service, the oil filter should be checked to ensure that it is properly fitted and has not degraded.

The Valve Gasket

This is a common cause of oil leaks - the valve gasket cover is located between the engine and the valve cover. It seals the oil inside. Over time the seal of the gasket can dry out and become more prone to cracks leading to oil leaks and engine failure.

Oil Drain Plug

The oil sump drain plug is a threaded pin with a head; it is located on the underside of the sump pan. If the threads become worn out or are misaligned, oil leaks can occur especially when the vehicle is in motion.


Accidentally driving over rocks and other debris can damage several components of the undercarriage of the car including the engine and the oil sump.

Overfilling The Oil

Whilst oil is essential for cars to run effectively, too much oil can cause the pressure on the crankshaft to increase, greater wear to the engine and potentially contaminating the spark plugs.

Camshaft Seal Leak

The camshaft seal is located in the cylinder head – wear and tear can cause these seals to degrade and leak oil. If there is a leak on the camshaft seal, there will usually be visible signs of oil in the engine itself – if the leak is more severe, smoke can sometimes be seen billowing out from the engine bay.

How To Prevent Oil Leaks

Regular Servicing and Maintenance

Regular servicing will ensure that the critical components of the car are in good working order and that the vehicle is safe to drive and running efficiently. It also helps to prevent any costly repairs further down the line as any problems, including leaks, are identified, and can be repaired before they become more serious. During a service, all major components of the vehicle will be inspected including the engine – any signs of an oil leak will be picked up on. The oil will also be drained and refilled, and the oil filter replaced if necessary.

Our Services

Longmynd Service Station offer all makes vehicle servicing at competitive prices. We are an independent garage and accredited Bosch car service centre, providing an exceptionally high level of service – all of our staff are fully trained through the rigorous Bosch Technical Training Programme to guarantee quality. For more information, get in touch today.