10 Best Synthetic Oils of 2021 (Full-synthetic & Blend Oils)

Jerry Wilson
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Do synthetic oils perform better than conventional oils?

The answer is no.

But in many cases an all-synthetic oil provides better lubrication performance and prevents wear and corrosion in modern engines.

But what is a synthetic oil?

According to Wikipedia, a synthetic oil is any motor oil that is composed wholly or partially of synthetic hydrocarbon oils made from crude oil, commonly called petroleum.

For more about synthetic oils, in this article we’ll reveal what the best synthetic oils of 2021 are.

NameCategoryProduct
Valvoline High MileageBest OverallValvoline High Mileage
Valvoline Advanced Full Synthetic SAE 0W-20 Motor Oil 1 QTBudget PickValvoline Advanced Full Synthetic SAE 0W-20 Motor Oil 1 QT
Shell Rotella T6 Full Synthetic 5W-40 Diesel Engine OilUpgrade PickShell Rotella T6 Full Synthetic 5W-40 Diesel Engine Oil

1. Valvoline High Mileage

Our rating: 9 / 10

Valvoline High Mileage

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Pros:

  • Great synthetic blend oil for maximum durability
  • Improves fuel economy
  • Contains motor oil additives like MaxLife that increase the life of the engine
  • Contains a number of D.O.T. compliant fluids that ensure optimal engine performance
  • Comes in a large bottle at about five litres

Cons:

  • Some customers complain that the oil comes with the odour of the previous oil
  • Smell of petroleum

This is one of the best in the market from Valvoline and it’s not hard to see why. This oil has all you would want from a good motor oil. It has been formulated using a blend of synthetic and natural oils that are good for maximum durability. It also ensures that your ride is smooth by improving fuel economy. It also functions as an additive since it contains excellent motor oil additives like MaxLife that increase the life of the engine. It also contains a number of D.O.T. compliant fluids that ensure optimal engine performance.

2. Shell Rotella T6 Full Synthetic 5W-40 Diesel Engine Oil

Our rating: 9 / 10

Shell Rotella T6 Full Synthetic 5W-40 Diesel Engine Oil

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Shell Rotella T6 Full Synthetic 5W-40 Diesel Engine Oil (Single Pack) is a premium brand of oil. It is a highly recommended oil at Shell gas stations. It is recommended by Shell for your diesel car and yes, your diesel motorcycle.

It is designed for gasoline or diesel engines with a low or partial quantity of natural base oils. Its fully synthetic base oils and other premium additives offer a superb overall performance, such as superior fuel efficiency for clean combustion. It prevents carbon deposits and lowers exhaust emission levels.

This is the 1-Gallon, Single Pack, New Packaging.

3. Valvoline Advanced Full Synthetic SAE 0W-20 Motor Oil 5 QT

Our rating: 9 / 10

Valvoline Advanced Full Synthetic SAE 0W-20 Motor Oil 5 QT

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Pros:

  • Available in different sizes
  • Can be used in cool and warm climates
  • Budget friendly
  • Environmentally friendly
  • Can be used for all engines, whether gasoline or diesel
  • Protects your engine from corrosion

The first synthetic oil for full engine protection, Valvoline’s Advanced Full Synthetic SAE 0W-20 qualifies for API SN /GF-5/CF/SL/SJ specifications. You can use this oil for gasoline, diesel engines, and any automotive application. It replaces conventional oil in passenger vehicles, SUV’s and even some light trucks.

4. Castrol 03084 EDGE 5W-30 Advanced Full Synthetic Motor Oil

Our rating: 9 / 10

Castrol 03084 EDGE 5W-30 Advanced Full Synthetic Motor Oil

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Pros:

  • 100% synthetic oil
  • Good flow and aeration
  • Contains advanced additive package
  • Good for high temperatures
  • No matter what the vehicle, this product is compatible with all engines
  • Good looking bottle

Cons:

  • Lacks lubricity
  • Needs to be warmed up
  • Can cause engine stalling

The Castrol 03084 EDGE synthetic oil is a great option as it features the latest additive technology that ensures lubrication and protection of the engine even as the temperature rises. Castrol also promises the oil will go a long way, considering that a single bottle can cover up 3500 miles.

The product is especially good at cold starts. As a result, your engine will be protected from thermal damage. It is also compatible with engine oils and transmissions. The product does a good job keeping the engine clean and free from corrosion.

However, the oil has been reported to need to be warmed up in the engine before it can work properly and guarantees the life of the engine. It can also cause the engine to stall.

5. Castrol 03101 EDGE 0W-40 A3/B4 Advanced Full Synthetic Motor Oil

Our rating: 9 / 10

Castrol 03101 EDGE 0W-40 A3/B4 Advanced Full Synthetic Motor Oil

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6. Royal Purple 51530 API-Licensed SAE 5W-30 High Performance Synthetic Motor Oil

Our rating: 9 / 10

Royal Purple 51530 API-Licensed SAE 5W-30 High Performance Synthetic Motor Oil

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You might think that Royal Purple's 51530 is crazy for its price, but it is far from it! The oil is fronted with Visco-Premium multi-grade synthetic base stocks, and is rich with superior performance additives such as Royal Purple's proprietary Synerlec Synthetic Motor Oil Technology, a high-performance friction modifier, in conjunction with a proprietary Synerlec Extreme Pressure additive.

Formulated with select friction modifiers and effective anti-wear technology, it is recommended for use in gasoline and diesel engines operating in extreme conditions. The product is a 5W-30 viscosity, but can be used in older engines that are not fully computerised.

Packaging is reasonable, coming in a 5 quart bottle that is resealable, and while it may seem expensive, just a single bottle provides a whole year's worth of oil for an average sedan. Additionally, if you live outside the U.S, the 51530 is available in countries such as Australia, Mexico, U.K, Canada, among others.

7. Royal Purple 51520 API-licensed SAE 5W-20 High Performance Synthetic Motor Oil

Our rating: 9 / 10

Royal Purple 51520 API-licensed SAE 5W-20 High Performance Synthetic Motor Oil

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Pros:

  • High Performance
  • Fully synthetic
  • Quick oil change

Royal Purple's 51520 is a premium blend made from a combination of ultra-premium hydrocracked and pure polymer synthetic base oils. It's good for both modern high-tech gasoline engines and diesel engines.

The company claims that its synthetic motor oil resists wear better and is more resistant to sludge and corrosion than ordinary 5W-20 oils.

8. Pennzoil 550046127 Platinum Full Synthetic Motor Oil

Our rating: 9 / 10

Pennzoil 550046127 Platinum Full Synthetic Motor Oil

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Pros:

  • Pack of 1
  • Anti-sludge technology

9. Castrol 03124 EDGE 0W-20 Advanced Full Synthetic Motor Oil

Our rating: 9 / 10

Castrol 03124 EDGE 0W-20 Advanced Full Synthetic Motor Oil

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Pros:

  • Prolongs Engine Life
  • Extends Oil Change Intervals
  • Minimizes Oil Consumption
  • Guaranteed By Car Manufacturers
  • Offers Lowest HTHS Viscosity

Cons:

  • Priceier Than Other Brands
  • A Bit Noisier Than Other Motor Oils

Castrol was always known as a synthetic oil pioneer. This technology, along with the help of other leading researchers, they have been able to create the 03124 EDGE oil that will help your engine last a lifetime! Castrol offers an oil change interval that is not offered by other leading brands.

10. Castrol 03083 EDGE 5W-20 Advanced Full Synthetic Motor Oil

Our rating: 8 / 10

Castrol 03083 EDGE 5W-20 Advanced Full Synthetic Motor Oil

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Pros:

  • 5W-20 viscosity
  • Full synthetic, high-quality engine oil
  • Protects against engine buildup
  • Increases fuel efficiency
  • 5 quart capacity

This synthetic, high-end engine oil from Castrol is fortified with an exclusive additive that helps eliminate harmful deposits and sludge in engines, ultimately increasing efficiency and the amount of miles that your engine can run on the oil before needing a change. It contains multi-grade zinc and phosphorus anti-wear protection that is constructed with technologies that are suitable for both turbo and non-turbo engines.

The 5W-20 viscosity creates additional lubrication that protects against engine wear and boosts fuel economy. It was created with high-quality base oils and additives, and has anti-corrosion properties that help prevent deposits from sticking to engine parts in the first place. It promotes sustained engine cleanliness and a high level of engine protection.

The perfect formula delivers the best overall performance that is geared towards durability and endurance.

11. Mag 1 20139 0W-20 Full Synthetic Motor Oil

Our rating: 8 / 10

Mag 1 20139 0W-20 Full Synthetic Motor Oil

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Pros:

  • 20% more Mileage than standard motor oils with less protection
  • Best for high performance vehicles

Cons:

  • Does not provide for strong protection in extreme weather conditions
  • Will burn off quickly at high RPM

This Shell Mag 1 20139 0W-20 Full Synthetic Motor Oil: 5 Quart is a unique grade motor oil that is designed to provide you with more mileage than standard. The motor oil is designed for use in high performance high mileage vehicles for road use.

The benefits of using this motor oil can be seen when used in high-mileage vehicles. When you look at it, you will realize that it provides for the lowest operating temperature compared to other motor oils. Other motor oils will provide for higher temperatures when used in high-performance models.

It will also be used for high-performance vehicles. It will also be used when considering the motor oil you want to use. It is the best for this as it has a unique formula that will be electrified by high performing vehicles. It has a heavy engine oil. It will be used for extended intervals before the next oil change. The motor oil has a high viscosity index that will minimize the oil use by up to 10 percent when compared with other normal engine oils.

12. Valvoline Advanced Full Synthetic SAE 0W-20 Motor Oil 1 QT

Our rating: 8 / 10

Valvoline Advanced Full Synthetic SAE 0W-20 Motor Oil 1 QT

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Pros:

  • Valvoline is an established brand
  • The product matches specifications
  • Great level of quality
  • Meets ASTM standards

13. Shell Rotella T6 Full Synthetic 5W-40 Diesel Engine Oil

Our rating: 8 / 10

Shell Rotella T6 Full Synthetic 5W-40 Diesel Engine Oil

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This synthetic blend oil from Shell is tough enough for your diesel truck and powerful enough for its new turbocharged engine. Its powerful engine oil provides you with extra protection against wear and improves fuel economy.

It’s a blend of fully synthetic basestock (non-BP), and premium synthetic basestocks that contains enhanced levels of detergents and dispersants for optimal performance. This blend of high quality oils keeps the engine clean, lubricated, and at a great temperature for optimal power, and fuel economy.

14. Mobil 1

Our rating: 7 / 10

Mobil 1

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Pros:

  • Engineered for High-Mileage Vehicles
  • Stops Friction Before it Starts
  • Helps Lessen Breakdown
  • Meets Or Exceeds API® SN & ILSAC GF-5

Frequently Asked Questions (FAQ)

What is the best full synthetic oil on the market?

For those who like higher performance or more synthetic oil, we suggest the Valvoline VR-1 Racing Oil. It is a good quality oil that has ingredients needed for lubrication and fuel economy.

The semi-synthetic oil we have selected is the Redline 42064. Again, it is a good quality oil that provides excellent protection with the needed extra ingredients for tuning.

For the cheap full synthetic oil, we chose the Royal Purple Max-Duty. This is a quality, reliable full-synthetic with good synthetic content.

Finally, for the cheap semi-synthetic oil, we selected the PureOne SAE30. This is an affordable oil that provides good lubrication for cars that don't need anything special for an engine tune.

What is better full synthetic oil or synthetic blend?

In a nutshell, full synthetic oils can provide you with better protection in very cold temperatures. Synthetic blend and mineral-based oil will be better in warmer weather.

Furthermore, as the label states, full synthetic oils will typically be more expensive. However, these oils will work better in very cold climates over extended periods of time. These oils have been around for eons and not much has changed. Within this category we'll look at two oil types: 1) Fully Synthetic Oil 2) Fully Synthetic Plus Oil

Is it OK to mix full synthetic oil brands?

Some owners like to use a combination of synthetic oil brands saying it helps ensure better protection. This may be true, but in reality, those three-quart bottles of Mobil 1 were formulated to work together and it would probably be better to stick with the brand the manufacturer intended you to use.

However, the fact that you can mix synthetic oils is good to remember if you’re ever in a bind. If you run out of Mobil 1 and need to buy more at the last minute, you’ll be happy to know that you can fill the tank with a little Pentosin instead.

Also, many people who mix brands elect to do so on a percentage basis. For example, if they use a 50/50 blend of Mobil 1 and Pentosin, they may toss in twice the amount of Mobil 1 than Pentosin, etc.

What is the best 5w20 synthetic oil?

Call it an old timer call it whatever you want, you can't argue with the fact that Pennzoil is one of the most respected and trusted car manufacturers in the world today. As you might expect from such an old and successful name, there are plenty of different grades of oil. If you drive a diesel; a manual or an automatic; are looking for a conventional, high mileage or a synthetic oil; there is a Pennzoil product to suit you and your vehicle.

This high-quality oil is one of the highest grade conventional lubricants available from Pennzoil. It is a 10W-30; it meets the recommended specification for the latest in Euro and American cars. On top of that; it will deliver everything you could want from a regular car engine. It is a great all-rounder for regular use in virtually any kind of car.

Conclusion

If you are looking for synthetic transmission fluid, or transmission fluid in general, you have many choices. You will want to compare different brands, including Mobil transmission fluid, Royal Purple transmission fluid, Redline transmission fluid and more. But before you do that, make sure you know a little about the transmission fluid durability, quality, and ranking, so that you can have the best transmission fluid you can have. That's why we've compiled this list in order to make sure you know exactly what you are buying and where you can find the best transmission fluid for your dollar.

Our Recommendation

NameCategoryProduct
Valvoline High MileageBest OverallValvoline High Mileage
Valvoline Advanced Full Synthetic SAE 0W-20 Motor Oil 1 QTBudget PickValvoline Advanced Full Synthetic SAE 0W-20 Motor Oil 1 QT
Shell Rotella T6 Full Synthetic 5W-40 Diesel Engine OilUpgrade PickShell Rotella T6 Full Synthetic 5W-40 Diesel Engine Oil