New Oil, Fluids & Additives

Choosing the Best 5W-40 Oil To Help Your Engine Run Smoothly

best 5w 40 oil

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5W-40 oil is a form of synthetic oil, which serves as a lubricant for machinery and vehicle engines. This synthetic oil is made from crude oil and put through a refining process. When complete, the oil is ideal for ensuring that an engine runs as smoothly as possible, whether it’s a truck, motorcycle, or other vehicles. That’s why it’s important to choose the best 5W-40 oil.

Best 5w 40 Oil: Quick Look

5W-40 Oil NameQualityPriceRating
Castrol 06249 EDGEA+$$
Motul 007250 8100 X-cessA++$
Liqui Moly 2332 Leichtlauf High TechA+$
Pennzoil Platinum EuroA++$$
Shell Rotella T6A+$$

What is 5W-40 Oil?

The number before the “W” in 5W-40 represents the cold viscosity rating of the oil. The number placed after the W shows the hot viscosity rating. This means that 5W-40 oil, when cold, behaves like a 5-rated single-grade oil. When it is hot, 5W-40 oil does not thin any more than a 40-rated oil.

Remember, when oil heats up, it typically becomes thinner. A single-grade oil will become too thin when it is hot for many modern engines, which is why many people now turn to synthetic and multi-grade oils to prevent the base oil from becoming too thin.

What are synthetic oils used for?

Synthetic oils like 5W-40 offer a host of benefits over traditional mineral oils. Using these kinds of oil can keep your engine in better condition, improve performance, and much more. These oils were also developed to cope with the high temperatures found within a modern engine. These synthetic oils flow more easily than traditional oils, and they can even provide better engine protection.

Better engine protection

When your engine first switches on, it takes a while for a traditional, mineral oil to get circulating throughout. This means that the unlubricated sections of the engine, at the beginning, experience friction, which can cause damage and wear over time. A synthetic lubricant, however, will begin circulating throughout your engine much more quickly. This means you won’t be risking any wear and tear on your engine when you first switch it on.

Improved fuel economy

On top of everything else, synthetic oils can improve overall fuel economy. When the engine first starts up, and the engine is using traditional mineral oils, the engine becomes less efficient. The oil moves more slowly throughout the system, whereas a modern synthetic oil will allow the engine to reach its peak efficiency more quickly.

Over many trips, this will reduce the amount of fuel consumed and allow your engine to run more efficiently. This not only saves you money on fuel, but it also means that your engine becomes more environment-friendly. Improving your fuel economy means you will cut your engine emissions. This is aided also by the fact that synthetic oils contain fewer impurities, like unstable hydrocarbons and sulfur.

Increased thermal and viscosity stability

With a higher viscosity index, 5W-40 and other synthetic oils maintain a more stable viscosity across a wide range of temperature. The oil performs well at low temperatures as well as high. Furthermore, with better oxidation and thermal stability, a synthetic oil can avoid a significant viscosity increase over time. This means you’ll have to change your oil fewer times, and experience overall less downtime.

Synthetic Oil

Does an old car need synthetic oil?

It’s perfectly reasonable to suggest that your old car managed to journey 100,000 miles using traditional oil, but that doesn’t mean you can’t benefit from upgrading to synthetic oil.

In fact, given the wear and tear that your engine will have experienced over the years, your car could benefit from a reduction in friction. By now, piston rings will have experienced some erosion caused by gas slipping past them—this is known as “blow by.” By switching to a synthetic oil like 5W-40, you can reduce any further erosion or damage to your engine, and keep your vintage vehicle running as smoothly as possible in its later years.

Furthermore, synthetic oil sometimes contains additives that are designed to improve ring sealing. Depending on the brand, your 5W-40 oil may contain seal conditioners that soften a stiff seal, as well as other additives that can stop oxidation and wear.

Tips for changing your oil

When it comes to changing your engine oil, there are some important things to remember. First of all, if your engine is cold, you should start it up and let it run for five minutes in order to warm up. If the engine gets too hot, let it cool down again for around half an hour. This means you won’t get burned during the changing process, and it also means that the oil won’t be able to fully circulate throughout the engine.

When removing the drain plug, avoid using an adjustable wrench. It can be dangerous using adjustable wrenches, and can even damage the plug. Use a properly sized, box-end wrench.

5 Best 5W-40 Oils

Here, GarageChief picks 5 Best 5W-40 Oils available on the market.

5W-40 Oil NameQualityPriceRating
Castrol 06249 EDGEA+$$
Motul 007250 8100 X-cessA++$
Liqui Moly 2332 Leichtlauf High TechA+$
Pennzoil Platinum EuroA++$$
Shell Rotella T6A+$$

Castrol 06249 EDGE

Castrol 06249 EDGE-5be9f7b23ec8a

Castrol 06249 EDGE offers a 42% improvement on the oil’s ability to fight deposits, which clog up the engine and negatively affect engine performance. As well as performance improvements, the oil can provide better protection compared to other conventional synthetic engine oils. Seals won’t get excessive wear and pistons should run smoothly upon startup.

The oil meets a number of manufacturer standards, including ACEA A3, ACEA B3, ACEA B4, BMW Longlife 01, Porsche A40, Volkswagen 502.00, and 505.00, as well as Mercedes Benz 229.1.

This synthetic motor oil was developed by Castrol, a trusted, reliable, and well-known motor oil brand. The oil is suggested by major car manufacturers and used in a range of high-end vehicles.


  • Quality synthetic motor oil produced by a reliable and famous motor oil brand
  • Protects against wear, tear, and oxidation


  • Pricier than some other synthetic oils
  • Foil seal makes it hard to open

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Motul 007250 8100 X-cess

Motul 007250 8100 X-cess-5be9f7b3c5224

Motul 007250 8100 X-cess is designed to be used in a variety of engines, whether gasoline or diesel. It is recommended for both OPEL 2.2 DTI and 2.0 engines, though it is widely used in many older and newer vehicles. This is a 100% synthetic oil product that is designed to reduce your oil consumption by reducing clogging.

With low volatility, this oil is designed for long-term use. Engines can run more efficiently and for longer, and the regularity of oil changes is reduced by using it.

Even cars like Audis, which tend to burn a lot of oil, can experience improved performance and fewer oil changes by using Motul X-cess. Furthermore, this brand sells for almost half the price of higher-end oils which provide all the same benefits.


  • Top opens with a funnel for ease of use
  • Affordable alternative to higher-end synthetic oils


  • Some users report that protection performance is not as good as claimed.

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Liqui Moly 2332 Leichtlauf High Tech

Liqui Moly 2332 Leichtlauf High Tech-5be9f7b5615c7

Liqui Moly 2332 Leichtlauf High Tech is a 5W-40 engine oil that is affordable and yet yields high-performance. This offers quick oil delivery even at low temperatures, and high-lubrication reliability can be expected at both very high and low temperatures.

On top of that, Liqui Moly’s 5W-40 engine oil provides a long engine service life. This occurs as a result of the protective characteristics of the oil, allowing it to protect pistons and other parts of the engine. It is also mixable; this means it can be used alongside other synthetic engine oils.

It is also known for its exceptional ability to keep engines clean, and it has been tested with catalytic converters and turbochargers. It saves users on fuel, it reduces pollutant emissions, and provides the best oil pressure, no matter the engine speed.


  • Extra-long engine performance
  • Mixability means it can be used with other oils
  • Approvals from major manufacturers


  • Affordable, but still not the cheapest available.

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Pennzoil Platinum Euro

Pennzoil Platinum Euro-5be9f7b73bbf1

Pennzoil Platinum Euro 5W-40 is made using their PurePlus Technology. This means that the synthetic oil consistently has a lower viscosity, even at temperatures as low as -40°F; an engine will require less effort to circulate the oil at extreme temperatures, ideal for those who live in colder climates.

The synthetic 5W-40 oil also offers better viscosity control, and it has performed well under oxidative test conditions; in fact, it performed better than other API Group 2 and 3 oils.

Using this synthetic oil, Pennzoil claims you can achieve an extra 550 miles per year, and the oil protects engine components from damage and wear, slowing down any loss of power. Pennzoil’s 5W-40 oil is designed for low-temperature oil flow and protects under extreme heat.


  • Designed to perform well under extremely low temperatures
  • Protects components from wear at high temperatures
  • Engines can run an extra 550 miles per year


  • Not the most affordable oil available

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Shell Rotella T6

Shell Rotella T6-5be9f7b915301

Shell Rotella T6 is a high-end synthetic motor oil that is recommended by a wide range of large vehicle manufacturers. The motor oil is designed to offer superior wear protection and cleanliness for your engine. This improves overall performance and allows your motor to run for longer. Shell boasts that the oil allows for 34% better wear performance, compared to earlier Shell Rotella formulations.


  • Improved performance over earlier formulations
  • Good high and low temperature protection


  • Some users claim seals often break during delivery.

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The Better Choice

At an affordable price, the Liqui Moly 2332 Leichtlauf High Tech oil appears to be the best 5W-40 oil available. The fully synthetic motor oil offers quick delivery, even at low temperatures. It also maintains good lubrication performance at high temperatures.

Engine cleanliness is also improved using this modern synthetic oil, and it performs better than many high-end alternatives. This oil has been tested using both turbochargers and catalytic converters, meaning it offers high performance and more eco-friendly performance in a wide range of vehicles and motors.

Liqui Moly’s synthetic oil is approved by BMW, Porsche, Renault, and many other manufacturers, and is generally more affordable than other options.