Why using the correct engine oil is vital for performance and longevity

The choice you make when purchasing engine oil will have an effect on the performance and longevity of your engine.

The choice you make when purchasing engine oil will have an effect on the performance and longevity of your engine.

Published Oct 6, 2022


Many motorists are not aware of what goes on under the bonnet of their cars - and even less so regarding what goes on inside the engine. Engine oil is literally the life blood of your car’s engine, and it’s important to realise that using the incorrect oil can lead to catastrophic results like engine failure.

Modern cars should not consume oil - and the only time the oil will be changed is at the service intervals prescribed by the manufacturer. However, as cars start getting older they might start using oil, which would then necessitate the topping up of oil between service intervals.

Don't be fooled by clever marketing and funky packaging. When it comes to oils, it’s all about specifications and approvals.

All lubricants - and engine oil in particular - should specify their performance level. Lubricant performance is tested against the industry standards as well as original equipment specifications.

All motor manufacturers specify a minimum performance level for lubricants to be used in that particular model, and it’s important to ensure that the lubricants you choose comply with that minimum performance specification.

Oils will be graded according to their performance specification as well as their viscosity. The viscosity of the oil is basically the thickness of the oil or how easily it flows. Higher figures represent thicker oils. Viscosity will also decrease as the oil gets hot. When the viscosity of oil gets too low as the oil gets thinner, it will fail to protect against metal-to-metal contact, resulting in accelerated wear of engine components.

Modern vehicle oils are classified as multigrade, which indicates that they contain additives to improve the temperature characteristics. Oils will be marked with two figures such as 20W50. The first figure indicates the extreme cold viscosity and the second figure specifies the viscosity at the operating temperature of the engine. It is very important not to use engine oil with a lower viscosity than the grade specified by the OEM. It is also very important to note that oils for petrol and diesel engines are dramatically different.

The topping up of oils is often done at forecourts, when the attendant asks to check the oil and water. This is not really good practice, as oil should not be checked immediately after the engine is switched off, but rather a few minutes after things have settled. In addition, the chances that the forecourt will have stock of the same oil that your car’s engine was filled with are slim. Furthermore, buying oil in small quantities is expensive.

The mixing of different oils in your engine is not a good idea. This can happen when you top up engine oil with a different brand or grade to what it was filled with at the last service. The different additives within the oil could react with each other, causing a breakdown of the lubricating properties or accelerating the build up of sludge in your engine.

Using the wrong oil can have costly implications, both in terms of inadequate lubrication in the engine itself, as well as the contamination of expensive emission control equipment.

Determining the correct oil to use starts with the OEM specifications, which are normally found in the operator’s manual of the vehicle - and this should be your starting point. Franchised dealers will be able to advise on the correct oil for your vehicle and will stock it in both their workshop and parts department.

Oils have various properties, which keep your engine running as it should throughout its entire lifespan and under all possible conditions. The choice you make when purchasing engine oil will have an effect on the performance and longevity of your engine.

Ask what oil will be added to your engine when you take your car for a service and keep a note of the brand and specifications. If your engine needs topping up of oil between services, it is a better idea to buy the correct oil from a dedicated supplier or franchised dealer and use that to top up the engine when needed.

Motus dealerships and their associated workshops represent a wide variety of vehicle brands and are specifically trained to offer advice on various maintenance related topics including which oils are correct for your vehicle.

For further info and tips, visit the Motus blog at www.motus.cars/blog and join the conversation on Facebook at www.facebook.com/motus.carssa

For super interesting videos, check out the Motus YouTube channel at www.youtube.com/channel/UCHEeNO-djwT4t3WJzgN6xRA