Best engine oil: For a super-smooth ride
The best engine oils promise to improve the performance, economy and reliability of your car
You might think that the primary purpose of engine oil is to lubricate the various parts you’ll find under the bonnet of your car. And you would be right: it prevents tightly engineered bits of metal clattering and scraping together – which could cause a breakdown and cost you dear. But the best engine oil does so much more besides.
Not only does it help to dissipate the heat generated from friction and the act of combustion in the cylinders, it also helps to keep an engine’s components clean. As an engine runs, it produces tiny particles that would otherwise build up in the engine. It’s for this reason that the golden oil you pour in the engine will, without regular maintenance, drain out in a oozy sludge. In addition, engine oil also seals microscopic imperfections in an engine’s components, and helps to prevent corrosion, too.
But the world of engine oil can be a confusing place, with a number of different types and grades of oil available – and choosing the wrong type for your motor could result in rough running, poor fuel economy or even engine failure. To determine which you should be using, refer to your car’s handbook, speak to your local dealer or use the tools available on many retailers’ websites.
Below, you’ll find our selection of the best engine oils currently available, based on the oil manufacturer’s claims and customer ratings across a range of retailers. First, read our guide on how to pick the best engine oil for your car.
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Best engine oil: At a glance
- Best fully synthetic oil: Castrol Edge | £36
- Best semi-synthetic oil: Castrol Magnatec | £35
- Best mineral oil: Millers Oils Classic Pistoneeze Engine Oil | £29
How to choose the best engine oil for your car
Do I need to use my car manufacturer’s recommended oil?
As long as you’re using the correct type and range of oil, you should be fine with any brand – although it’s preferable to opt for a product from a reputable manufacturer. Bear in mind that a car manufacturer’s recommended oil – sometimes referred to as OE (Original Equipment) oil – will have been used during a car engine’s development. This means the car engine’s design and tolerances will be based on that particular oil behaving in a particular way. Use something else and you may also risk invalidating your warranty.
What’s the difference between mineral, fully synthetic or semi-synthetic oil?
Mineral oils are a by-product of the crude-oil refining process and are widely used in older, more basic engines. They’re generally cheaper than semi- or fully synthetic oils, although many classic-car owners are happy to spend more for the best. Synthetic oils are at the opposite end of the spectrum, offering huge benefits for high-performance engines. They, too, are based on crude oils; however, they undergo complex chemical transformations that modify the oil and remove impurities. As a result, they flow well at low temperatures and remain stable at high temperatures.
Semi-synthetic oils represent a halfway house. As a blend of 100% synthetic and mineral oils, they come in cheaper than the former, but still offer many of the properties of the latter.
Not all types of oil are suitable for all engines, so always check your car manufacturer’s recommendations.
What do the numbers on an oil bottle mean?
On each container of engine oil, you’ll see a string of digits such as 5W-30. These relate to the viscosity – the measure of a fluid’s resistance to flow. It’s essential to choose the correct grade of oil for your particular car’s engine.
The first number rates the oil’s viscosity at 0ºF (-17.8ºC); the lower the number, the less thick the oil becomes in winter (which explains the W digit). The number after the dash refers to the oil’s resistance to thinning at high engine temperatures. Once again, it’s essential you use the correct grade of oil for your engine.
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The best engine oil you can buy in 2023
1. Castrol Edge: Best fully synthetic oil
Price when reviewed: £36 | Check price at Halfords
Castrol claims its Edge oil is the best it’s made in the brand’s 115-year-plus history, and is the recommended oil for Jaguar, Land Rover and Volvo cars. Users certainly agree, with 4.8 star ratings across thousands of reviews on Amazon and Halfords’ website.
Edge contains “Fluid Titanium” technology, which sees it become stiffer when under high pressure, helping to maintain clearances within the engine while reducing friction. Castrol claims a 20% reduction in friction compared with oils that don’t use Fluid Titanium, stating that it can boost engine performance by up to 10%.
Key specs – Bottle size: 4 litres; Available grades: 0W-20, 0W-30, 0W-40, 5W-30, 5W-40
2. Castrol Magnatec: Best semi-synthetic oil
Price when reviewed: £35 | Check price at Halfords
We’ll begin with a word of caution – because most of Castrol’s Magnatec range is fully synthetic; only 10W-40 and a version of the same grade suitable for diesel engines is semi-synthetic. But you can’t argue with near-five star ratings on both Halfords’ and Amazon’s websites for cars requiring 10W-40 (the most commonly available grade of semi-synthetic oil).
Castrol says Magnatec’s molecular construction results in the oil acting as a “force field” around components. In effect, this means the oil sticks to surfaces to ensure coverage during warm start – where 75% of engine wear occurs – and start-stop cycles. Castrol boldly claims a 50% reduction in engine wear, making this oil good for reliability, economy and performance.
Key specs – Bottle size: 4 litres; Available grades: 10W-40
3. Millers Oils Classic Pistoneeze Engine Oil: Best mineral oil
Price when reviewed: £29 | Check price at Halfords
There’s no mistaking the target audience for Millers’ Pistoneeze oil: its bright red metal canister with an Aston Martin on the label wouldn’t look out of place on a postwar garage shelf. Millers says it’s primarily aimed at pre-1980 vehicles, which were designed to be lubricated by the multigrade oils available at the time.
This mineral oil uses modern additives but retains the viscosity of that day for correct lubrication, and is suitable for higher-mileage classics – both petrol and diesel – where high viscosity helps reduce oil leaks. It’s offered in 10W30, 10W40, 15W40, 20W50 grades, and is rated highly by users of both Halfords and Amazon.
Key specs – Bottle size: 5 litres; Available grades: 10W-30, 10W-40, 15W-40, 20W-50
