What is the Best Engine Oil for My Car?

Better engine health starts with the type of oil you use in your car. Oil protects and lubricates the engine to stop corrosion and wear, preventing friction and making sure everything runs smoothly. If you use an inferior product that’s not of the best quality, you’ll not only have to change the oil more often, but you might not get the protection and performance your engine needs.

Refueling and pouring oil into the engine motor car. Energy fuel concept.

Anyone who’s ever looked at engine oil will know just how confusing choosing the right product can be. With lots of different grades and options, finding the right one for your car can be tricky.

In this guide, we’ll take a look at the different oil grades and what they mean, as well as some of the other points to consider when buying oil for your car.

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Engine Oil Grades Explained

Oil Grades

Refueling and pouring oil into the engine motor car. Energy fuel concept.

Pretty much every modern car uses multi-grade engine oil; this is essentially a mix of two oils with different viscosity levels. Multi-grade oil was developed for convenience, as, previously, drivers had to change their oil for summer and winter driving conditions.

The viscosity of multi-grade oil is represented by a number grade from – to 20, e.g. 10W-40. In this case, the 10W (w – winter) means that the oil has a maximum viscosity rating of 10 in low temperatures, offering protection down to an average of -20°C. Thin oil is better for winter because it circulates through the engine faster from a cold start, so your engine is better protected. Remember: the lower the number, the thinner the oil.

If you buy an oil with a ‘W’ grade, you can tell a lot about the protection it offers by the viscosity. The table below shows the protection you’ll get from your oil in cold weather conditions:

‘W’ Oil ViscosityWinter Temperature Protection

The ‘40’ in the above example also gives an indicator of the oil’s viscosity, but this time it measures how thin the oil is at 100°C. Again, the lower the number, the thinner the engine oil, so a ‘30’ is thinner than a ‘40’ at 100°C.

Because multi-grade engine oils are designed for both winter and summer driving conditions, they’re safe to use in engines throughout the year, and aren’t affected by extreme temperature change. However, it’s important to use the engine grade recommended for your car, as the oil pumping system is designed for a specific viscosity of oil.

What’s the Difference Between Synthetic, Part-Synthetic and Non-Synthetic Oil?

male customer buying engine lubricating oil in the car supermarket. Difficult decision which motor oil to buy

Ever wondered why there’s such a difference in price between different brands of engine oil? There are a couple of things that affect the price of engine oil, and we’ve listed these below:

Fully Synthetic

The most expensive type of oil, fully synthetic offers a range of benefits over other oils:

  • Lasts longer between oil changes – you don’t have to change it as often, which is convenient, better for the environment as there’s less waste and can help offset the cost of spending more on the oil.
  • Improved fuel efficiency – synthetic oil flows better, allowing engine parts to turn more quickly for better efficiency and lower emissions.
  • Offers better protection – it withstands extreme temperatures better, in both hot and cold conditions. If you do a lot of long distance driving or have a high performance car the engine is likely to get to higher temperatures, so a synthetic or part-synthetic oil is recommended.


Part-Synthetic oil is exactly as it sounds – a mixture of synthetic and traditional oil, so you get a mixture of benefits:

  • Cheaper than fully synthetic oil
  • Offer better protection and improved efficiency compared to traditional oil, but not to the standard of fully synthetic options.


Non-synthetic oil is the traditional engine oil, and is less “clean” than synthetic versions which have been engineered to have fewer impurities, however it is not “bad” for your car.

  • Cheaper than synthetic or blended options
  • A good budget option


How to Find Out What Oil Your Car Needs

Mechanic reading instructions manual and replacing broken part

Recently bought a car and not sure which sort of engine oil it uses?

There are loads of different specs of engine oil represented by different letters – and this is often where buying engine oil can get confusing. Car manufacturers each have their own oil grade specification which they recommend you use in their cars, so make sure you use a product that lists your car’s manufacturer spec.

There are a couple of routes you can go down to find out the recommended oil type:

  • Owner’s manual –The manual will tell you the exact grade and specification for your type of engine, so make sure you buy a product that corresponds with this.
  • Redex Oil Finder – Visit our oil finder tool to input your registration and get an instant link to a suitable oil for your car.

If you want peak performance from your engine, you can count on Redex. Our fuel additives and engine oil range are developed to improve engine health, so you can enjoy a better drive. For more information and advice, visit our homepage.