What oil does my car need?

Oil ensures that an engine’s moving parts are properly lubricated, allowing it to function smoothly. And today’s oils feature additives that help keep the engine clean while guarding against corrosion and combat the formation of sludge.

A modern car requires oil that can remain in a stable state between service periods, which might mean lasting for thousands of miles. If you’re baffled by the range of engine oils available, don’t worry, we’re here to explain. Before we talk about the different types of engine oils, let’s go through some of the essentials.

Why should I check my car’s oil level?
Establishing the correct oil level is crucial. While cars today are more technologically sophisticated than ever, there are certain constants that remain. Dropping below the required oil level can cause major problems. By making sure your car’s engine oil is appropriately topped up on a regular basis, you’ll significantly lengthen the life of the engine while maximising vehicular reliability and safety.

An engine is a complex piece of machinery that can cost a great deal to repair if it falls into disrepair. Oil is essential because it lubricates the engine, ensuring less likelihood of damage and premature wear and tear. Ultimately, correct oil levels deliver enhanced fuel efficiency, thus saving you money in the long term.

Which engine oils should I use?
The first thing to do is check your automobile’s handbook, which will outline the types of engine oil that are compatible with your vehicle. If you don’t have access to a physical copy, you should be able to find one free online. Alternatively, contact your car’s manufacturer – or your local Thurlow Nunn dealership.

Why are engine oils different?
Engine oils are classified according to their viscosity (how thick or thin they are), which is altered by fluctuating temperatures. That said, multi-grade engine oils are designed to work effectively within a wide spectrum of temperature changes.

Checking viscosity
Oil temperature ratings range from 0W to 25 (cold) and from 20W to 60 (hot). The cooler the temperature, the thinner the oil becomes; the hotter the temperature, the thicker the oil gets. Oil containers are marked according to temperature ranges. For instance, a container might feature a 5W-30 rating or a 5W-40 rating and so on.

The first number denotes viscosity in cold weather (the ‘W’ stands for ‘weather’) while the second number refers to viscosity at higher temperatures.

Engine oil specifications explained
In Europe, oil performance specifications are governed by the European Automobile Manufacturers’ Association (which goes by the ACEA acronym). Since not all engines are the same, it makes sense that there are different oil specifications. And to make things a little more complicated, several car manufacturers have developed their own engine oil specifications, Mercedes-Benz and Volkswagen, in particular. For best results, always go by your car manufacturer’s specification rating when purchasing oil. That said, unofficial equivalents are available – and if deemed acceptable by your car’s manufacturer, they can be used on an emergency top-up basis.

ACEA specifications
The ACEA has created numerous oil-specification categories, beginning with A1 (fuel economy) and ending with A5 (fuel economy plus extended drain capability). Meanwhile, diesel categories start with B1, rising right to E9.

If you own a diesel car which is fitted with a diesel particulate filter (DPF), you will need to use an appropriately low-SAPS (sulphated ash, phosphorous, sulphur) oil. Low/mid SAPS oil is broken down into three categories: C1, C2 and C3 – using any other kind of oil can cause the DPF to become blocked.