Engine oil: What causes your car to burn it?

Most car owners – even non-enthusiasts – know that engine oil lubricates engine components. It is not meant to be burned – that’s what petrol (or diesel) fuel is for.

So, when you check your oil level and find it to be low (or see a warning light indicating this), there are only two possible explanations for this.

The first is that there is an oil leak. You can usually tell by just checking under your parked vehicle.

If you find no evidence of leaking oil, then the only other explanation is that your car is burning it.

How do engines end up consuming oil?

The most common cause of high engine oil consumption is worn piston rings. Piston rings are made from special alloys. They function as the seals between the combustion chamber and crankcase of the engine.

Piston rings are designed for a very tight fit and even accommodate thermal expansion. This is how they are able to prevent engine oil along the cylinder walls from seeping into the combustion chamber.

Over several thousands of kilometres, the pistons and cylinder walls will experience wear, compromising the seal. This is when oil seepage begins to occur.

Symptoms of worn piston rings

There will be a noticeable increase in oil consumption and eventually, bluish-grey smoke spewing out the exhaust pipe. The latter is the most obvious sign that a car is burning oil.

Using a high-quality engine oil will prolong the life of piston rings and delay the onset of cylinder wall wear. This is why regular and timely servicing is so crucial.

However, over time, wear will still set in.

If you continue to run a car with worn piston rings, the vehicle’s overall performance will deteriorate. And engine oil – which is also formulated to keep a motor clean – will become contaminated.

Remember, piston rings act as a barrier. Once worn, they not only let oil into the combustion chamber, but also allow exhaust particles (and other stuff) to contaminate the engine oil.

This further exacerbates engine wear – not just to the cylinders but also to other parts such as the crankshaft bearings.

What's the solution?

Replacing the piston rings is the only remedy. Do not believe anyone who says they have a “special formula” that will “rejuvenate” the piston rings.

Additives are nothing more than temporary relief. Some may even cause further engine damage in the long run.

ALSO READ: Are diesel cars harder to maintain than petrol cars?

This article was first published in Torque.