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12/09/2017 Event


Did you know that both your driving style and your car's engine design affect how often you have to top up the oil that lubricates the crankcase? Here Total explains why.

Even though the right amount of oil was added the last time you took your car into the auto repair shop, you'll probably have to top up every now and then. Why is that? What happens to the oil? Why isn't there a puddle of oil under the car when the dipstick shows that the oil level is low? Are gremlins making off with it?

Well, the real answer is that your car consumes both fuel and oil. This post outlines some of the reasons cars lose oil.

The Causes of Engine Oil Consumption

The first thing to remember is that all vehicles consume oil. This is because the oil enters the combustion chamberand is burned along with the fuel. That’s why it’s important to check the oil level regularly.

More specifically, a car’s oil consumption is determined by two main factors: engine design, as this is what carries the oil into the fuel distributor, and your driving style.

Engine design impacts combustion and exhaust

With regard to how the vehicle’s design can influence oil consumption, something we will cover in greater depth in an upcoming post, it’s important to remember that oil constantly circulates around the combustion chamber. That means that some will end up inside the chamber. In fact, the engine’s design makes it necessary for the oil to enter the area around the piston and around the valves (seat, stems and guides, etc.).

The amount of oil that enters depends on the clearance between the parts. Today’s engines have less clearance. That means less oil is consumed, because it has more contact with the components and cannot reach the combustion chamber as easily. This is one reason why you need to use premium oils specific to the engine type. More fluid SAE viscosity grade oils are recommended. But whatever the clearance, each time the piston reaches the top dead center(maximum engine compression) a certain amount of oil is sucked into the combustion chamber and burns.

But combustion is not the only reason you lose oil. It can also evaporate in other areas. More specifically, the oil that lubricates the exhaust valve is subjected to very high temperatures, producing high-pressure gas that damages the oil or causes it to evaporate.

These are the reasons why cars consume oil. In some cases it’s due to combustion in the chamber and in others, exhaust.

Why do two cars of the same make and model use different amounts of oil?

The oil consumption covered so far is inherent to each vehicle and depends on its design. But two identical cars sometimes consume different amounts of oil. This is because drivers have their own individual driving styles.

Whenever the gases from the combustion chamber are emitted, oil is consumed in the area around the exhaust valve. As engine speed increases, the amount of exhaust increases too and more oil is consumed.

So the mysterious case of the disappearing oil is due to your driving style. Given that, the amount of oil consumed increases with vehicle and engine speed. Similarly, the car's design plays an important role; the clearance between engine components affects oil consumption.