Engine oil: Understanding motor oil

You probably already know the basics of how a car engine works. An engine powered by fuel causes the wheels to turn. You don’t need to know about aerodynamics, electronics or what fluids like engine oil and coolants do.

However if you want to get the most out of your vehicle you should learn the details behind how it works and what you can do to improve performance. Therefore in this series of articles we are going to dig deeper into the engine, concentrating on engine oil.

Why do cars need oil?

Every car is able to move thanks to fuel combustion. Basically, a mixture of fuel and air (in blue)  enters each cylinder where the piston compresses it, causing it to combust. That results in the rotation of the crankshaft and this rotation is subsequently transferred to the wheels.

Although the cylinders are missing from the image for the sake of clarity, you can see that there are lots of metal-to-metal contact points which, if not properly lubricated at all times, may cause severe damage to the engine.

To ensure lubrication, oil gets pumped from the sump located below the engine to all metal-to-metal contact points such as the pistons, crankshaft and camshaft. The oil then drips back to the sump.

As you can see, this procedure reduces friction drastically in critical points of the engine, which easily reach more than 300ºC and need this lubrication to control temperature and avoid malfunctions.

When do I need to change engine oil?

Of course, oil doesn't last forever. When passing through its circuit, the oil collects waste from the fuel combustion. Over time its effectiveness will diminish.

On top of this, your driving style or your car’s design can cause the oil to burn without you even noticing. This could happen when oil gets in the cylinder and mixed in with the fuel, causing it to also burn.

For these reasons, you should change engine oil regularly and always check its light indicator. Depending on the vehicle and the type of oil, synthetic or conventional, is advisable between 10,000 and 30,000 km. Or 12 and 24 months respectively.

If the vehicle is modern and run with synthetic oil, it is close to 30,000 km, while if the vehicle has more than 10 years or the oil is conventional, the opposite.

To know with precision when to perform an oil change, you should take a look at your vehicle’s manual. Finally, if your current oil’s viscosity is higher than the recommended one, stick with the one you have.

Stay tuned!

In the coming weeks we will talk about oil viscosity, synthetic vs conventional oils and how additives can improve a motor oil's performance.