Why is my car leaking oil?

Take a tour around the car parks of Shropshire and you’ll most likely see a rash of oil stains on the ground that have leaked from cars while they have been parked, but surely it’s impossible to continue to drive when oil is escaping from the engine?

While it’s right to take any signs of an oil leak seriously, the existence of a leak doesn’t mean that driving is impossible, nor that your car’s engine is on the brink of total failure. Instead, a measured response is necessary that will enable you to continue to motor, without placing your car’s engine at risk of developing serious and costly defects.

Whether you should immediately engage in panic mode depends on the size of the oil leak and its location. While some oil leaks tend to drip constantly, even while a vehicle is parked with the engine turned off, others are only problematic while the engine is running, so the amount of oil that escapes depends on the amount of driving you do and the distance you cover in an average day. In general, the further you drive, the more oil you can expect to lose and the sooner you’ll have to top up to protect your engine from serious damage.

Another important factor that will determine how quickly you need to have an oil leak investigated is the amount of oil that your car holds. Most cars can store between four and six litres of engine oil, but some cars can hold more, meaning a small leak is less likely to cause immediate problems than in a car that has a much lower capacity.

Ultimately, your aim is to ensure that sufficient oil remains in your car’s engine while you await the opportunity to have the source identified by a professional. Only a plentiful supply of oil to the engine will ensure that the major components, such as the pistons, rods and crank shaft, are properly lubricated. Running short on oil will rapidly cause significant damage to these components and quite probably render your entire engine unusable, meaning complete replacement is likely.

As it is virtually impossible to judge how much oil is leaking from your car’s engine simply by looking at the stain on your drive, it is essential to regularly check the remaining oil level by reading the dipstick. Not only will this help you to gauge how much oil remains, but it will also enable you to determine how serious the leak is and how quickly oil is escaping from the reservoir where it is stored. Modern cars use very little engine oil, so any decrease in the oil level indicates a moderate to rapid leak; in an older car, bear in mind that oil is used up more quickly, especially if you are completing long distances regularly.

An oil leak, however slight, should never be ignored. If oil leaks onto the rubber hoses and seals beneath the bonnet of your car, they can deteriorate, causing additional problems, while engine oil is also a potential fire hazard that must be taken seriously.

Fortunately, most oil leaks are not serious - they're often the result of seals or gaskets that have degraded. Replacement of these worn components is inexpensive, meaning the oil leak can be easily fixed without extensive repair work and high labour charges.

Unfortunately, as a motorist it’s difficult to determine how serious an oil leak is, but it’s vital not to make the worst case assumptions about the condition of your car’s engine as a whole. Take immediate steps to ensure there is sufficient oil in your vehicle to lubricate the engine and arrange a convenient time to have your car examined by a professional, so that you can be fully informed about the extent of the leak and the costs involved in solving the problem.