Car Maintenance: Different types of oil explained!

One of the main ways to keep your vehicle in tip-top condition is by looking after your engine oil. Making sure you have the right level is vital. But you need to ensure you are using the right TYPE of oil when you do find you need a little extra in the system.

There are a number of different types of oil and understanding which one is the right one for your vehicle can seem daunting. Here is a brief guide to the types of oil available and what the numbers on the bottle mean.

Oil can be Conventional, Fully Synthetic or a blend of the two, there are differences between them which affect how it performs in your vehicle:

Conventional Motor Oil: this is refined crude oil that has gone through a simple refining process.

Fully Synthetic Oil: this has not only gone through a refining process, but it has been broken down to a molecular level and impurities removed. These specialised compounds along with various additives are designed to provide greater levels of performance and protection to the engine than conventional oils are able.

Synthetic Blend Oil: This is simply a mix of the Conventional and Synthetic oils, it won’t have the same level of additives as the synthetic oil but will be able to offer some of the performance and protection properties.

What do the numbers mean?

The grade is shown by two numbers separated by a ‘w’ for example 5w40. The numbers are an indication of the oil’s resistance to flow, or in other words, how thin it is. The number before the ‘w’ is the resistance at winter or cold temperatures. The lower the number the better the performance in cold conditions. The number after the ‘w’ is the resistance at 100ºc, with a lower number meaning the oil is thinner. You should look to use a grade that is specified in the vehicle’s handbook.

API is an acronym for American Petroleum Institute, there are two main categories used for vehicles ‘S’ for petrol vehicles and ‘C’ for diesel vehicles. Unless you are driving a vintage vehicle, you would look for the two latest versions, these being ‘SM’ for Petrol and ‘C14’ for diesel.

You might also see on the bottle ACEA, this is the European Automobile Manufacturers Association. They use a number and letter classification, which can be broken down as follows:

  • Petrol
  • Diesel
  • Fuel economy
  • Standard performance
  • High performance
  • Direct injection
  • Combines economy and performance

For example, an oil rated A1 is designed to offer fuel economy in a petrol vehicle, whilst B3 oil would offer high performance in a diesel vehicle. There is also a letter ‘C’ grade, this can be used in both petrol and light duty diesel engines and is designed to offer economy and performance.

What next?

Once you have identified the correct oil to use from the owner’s manual, look to buy the best quality you can in your budget. This will offer the greatest benefits including prolonging the engine life, reduced fuel economy and should not need to be topped up as often.

The owner’s manual will advise you on how often you should check the oil level and how often it should have a complete change. There is an acceptable level of oil loss for every engine. Over time, however, contaminants will make their way into the oil and just topping it off will only increase the ratio of these contaminants. It is important to completely renew the oil in the engine on a regular basis.

If you think it is time for an oil change or you’ve noticed that you are topping the oil off more frequently than normal, drop Dereck and the team at SLVS a call and we’ll get your vehicle booked in for a check-up.

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