How to choose the right oil for your car

To say there’s a lot of variety when it comes to engine oils is an understatement.

If you’ve ever stood before shelves of engine oils and felt overwhelming confusion, you’re not alone. Each type of oil serves a different driving style, car make, and even different climates, so picking the correct one will help your car run at its full potential.

We’re here to break it down for you so that by the end of this article you’ll understand Australia’s engine oil classification systems, oil viscosity ratings, API and ACEA standards, and the various types of oils available.

Not sure which oil is right for your car? Please call our expert team on 1300 772 579 or click here to find your nearest store.

Engine oil viscosity in a nutshell

Viscosity ratings tell us how thick the oil is at a given temperature. Most car manufacturers recommend multi-grade oils, which are thinner at cooler temperatures to allow for faster circulation and thicker in high temperatures to protect the engine. The Society of Automotive Engineers (SAE) rating is what we use in Australia to determine engine oil viscosity. With SAE ratings, the higher the number, the thicker the oil.

A common multi-grade oil viscosity rating is 10W-40. The first part – 10W – indicates how the oil will flow at cold temperatures (the ‘W’ means ‘winter’), while the second part indicates how it will behave in high temperatures. The lower the number in the first part, the better it will perform in cold temperatures, and it works in reverse for hot weather. Given Australia’s mild winters, it’s not usually necessary to purchase engine oil that performs best in cold climates.

Your car’s manual will specify the ideal oil viscosity, so it’s best to stick to that or something pretty close, unless you need to alter it for use in extreme temperatures.

Service classifications

In Australia, the American Petroleum Institute (API) service classification is the most commonly used. The letter ‘S’ denotes a petrol engine oil, while ‘C’ is used for diesel engine oils. Each letter is followed by a second letter, which indicates the quality standard of the oil. It starts with the letter ‘A’ and as the alphabet progresses, so does the oil’s quality.

Other service classifications you may see in Australia include Association des Constructeurs Europeens d’Automobiles (ACEA), International Lubricant Standardization and Approval Committee (ILSAC), and Japanese Automotive Standards Organisation (JASO). You may need to know these if you drive a European or Japanese car, particularly if your car’s manual recommends engine oil based on these classifications.

Types of oil

There are three main types of oil available: mineral, synthetic, and semi-synthetic. Most modern cars work best on synthetic oils, while turbo-diesel engines like semi-synthetic, and older, classic cars prefer mineral. Again, your car’s manual will specify which type of oil you should be using.

What does all of this mean?

When you pick up a bottle of engine oil, you’ll probably notice the viscosity rating first. This will look something like ‘SAE 10W-40’. Stick to what your car manufacturer recommends, unless you are driving in extreme temperatures.

Specifications will probably be on the back of the bottle and may look something like ‘API SL/SJ/CF’. Remember, the ‘S’ means petrol, the ‘C’ means diesel, and the second letter indicates the quality. An ACEA specification will look something like ‘ACEA A3, B3, B4’.

The type of oil will also be clearly printed on the front of the bottle. Most new cars will take synthetic oil, which tends to be a little more expensive than semi-synthetic and mineral oil. However, it’s important that you don’t attempt to cut costs by buying a cheaper type of oil.

If in doubt, drop in to your nearest Kmart Tyre & Auto Service and we’ll be happy to help you out!


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If your car is due for a service or needs any kinds of mechanical repair, then call us on 1300 772 579 to book a service, or here to find your nearest store..

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