- oil
How Do I Know Which Oil I Need?
Updated 6 Jan 2025
Joel Ilton
Answer
Choosing the right oil for your car can be confusing, especially for those less mechanically minded.
The average driver stands at the shelf in utter confusion when it comes to picking the right engine oil.
What do all the letter and number combinations mean, you ask? Let’s get into it.
- It has to do with how the oil performs in various operating temperatures
- Driving styles
- Make/ Model of the car
Viscosity Index (VI) ratings are a measure of showing the change of viscosity with variations in temperature.
Basically, it tells us how thick the oil is at a certain temperature.
An example viscosity rating is 10W-40. 10W represents how the oil will flow at cold temperatures with the ‘W’ standing for winter.
The lower the number, the better it will perform in cold temperatures. The 40 indicates how the oil behaves at high temperatures, in contrary the higher the number the better it performs in hot weather.
Which oil is right for me?
It is common for car manufacturers to recommend a multi-grade oil, this means at cooler temperatures the oil is thicker to protect against engine wear.
As the engine heats up the oil becomes thinner, which then circulates faster to give adequate lubrication.
This also reduces friction, which in turn increases fuel efficiency.
Your owner’s manual will describe the correct oil grade required in your vehicle, and which temperatures these grades are suitable for.
If your car is diesel and fitted with an exhaust particulate filter (DPF), then keep an eye out for specific oil.
This oil usually has a ‘low SAPS’ label to differentiate it from other oils.
This oil has reduced amounts of sulphur and other elements, as these can block the DPF if the incorrect oil is used.
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Written By
Joel Ilton
Finding a passion for cars from a young age, Joel carried out work experience as a mechanic whilst at school before starting an apprenticeship after finishing year 12.
Joel is now the Workshop Manager at Robina Volkswagen.