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The Best Synthetic Motor Oil 2021

Best Synthetic Oil

Synthetic oil is the best motor oil you can provide a gasoline or diesel powered vehicle. It’s the most important service product and regular oil changes ensures the engine continues to perform as expected.

The reason for oil being so important is due to the fact it lubricates the engine to reduce wear, friction and the break down of any components from engine heat. It also helps to clean the dirt as well as passing heat around the engine for optimum performance all year round.

If you want a quick answer, the best synthetic oil is the Mobil 1 94001 5W-30, which has superior engine wear protection due its lubrication in low and high temperatures. However, if you require a budget option, the Valvoline SynPower is the best alternative that’s available in several viscosity ratings.

To rate the synthetic oils within this article, we based our recommendations upon hours of research, our own experience and multiple factors. The factors that we considered included their brand reputation, wear protection, value for money, viscosity availability, additional additives and bottle sizes.

Table of Contents

Best Synthetic Motor Oil Comparison

Synthetic Motor OilFuelViscosity
Mobil 1 94001GasolineMultiple
Castrol 03101Gasoline0W-40
Pennzoil Ultra PlatinumGasoline5W-20
Shell Rotella T6Diesel5W-40
Royal Purple 51530Gasoline5W-30
Valvoline SynPowerGasolineMultiple
Amazon Basics ApprovedGasolineMultiple
Liqui Moly 2041rBoth5W-40
Castrol GTX MAGNATECGasolineMultiple
Motul 8100 X-cessBoth5W-40

Servicing your car with synthetic motor oil increases the engine’s life and ensures it remains running smoothly. Although full synthetic is more expensive than conventional oils, the range of benefits makes it a worthwhile investment. It’s well-known that many of the cheap oils are often recycled, which makes it less beneficial for the motor and it won’t perform as you would expect.

Below is a list of the best synthetic oils that provide optimum performance and engine cleanliness, which helps to increase the longevity of your motor.

The Best Synthetic Oil

1. Mobil 1 94001 5W-30 Synthetic Motor Oil

Mobil 1 94001 5W-30 Synthetic Motor Oil
Mobil 1 is one of the most reputable manufacturers of synthetic oil and for good reason too. This 94001 5W-30 motor oil is one of their most popular and is suitable for turbo-charged, super-charged or multi-valved fuel injection gasoline engines.

The Mobil 1 94001 is highly recommended for everyday driving and modern cars that require a 5W-30 oil. The advanced formula is packed with additives that prevent wear and tear, provide thermal and oxidation stability and so much more.

Other features of the Mobil 1 94001 include:

  • 5W-30 oil
  • Outstanding engine wear protection
  • Improves fuel efficiency
  • Extra protection against sludge and deposits
  • Suitable for low and high temperatures (-53 to 500ºF)
  • Bulk buy option for better value

Overall, the Mobil 1 94001 is the best synthetic oil for your car that provides superior lubrication for all moving parts. It’s the first choice for many people that want to give their car’s the best possible synthetic blend to improve all-round performance.

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2. Castrol 03101 EDGE 0W-40 Synthetic Oil

Castrol 03101 EDGE 0W-40 Synthetic Oil
The Castrol 03101 Edge formula claims to have a 42% better rating of fighting power to provide the highest level of protection. The advanced synthetic oil also features excellent lubrication to prevent wear and tear and allows your car to drive at maximum power.

Castrol is well-known for working with high end car manufacturers such as Volkswagen, Jaguar and Land Rover. This means they are able to rigorously test and improve their motor oils worldwide thus making them a market leader.

Other features of the Castrol 03101 Edge Synthetic include:

  • 0W-40 viscosity rating
  • Reduction of metal-to-metal contact
  • Titanium technology for optimum performance
  • Reduces engine deposits
  • Enriched with premium additives
  • Tested under extreme pressure
  • Available in multiple different viscosity and bottle configurations

The Castrol Edge is an advanced synthetic oil that’s been tested under intense pressure and is one of the best synthetic oils on the market. By using the Castrol 03101 0W-40 formula, you can expect reduced engine noise as well as a much smoother engine.

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3. Shell Rotella T6 5W-40 Diesel Motor Oil

Shell Rotella T6 5W-40 Diesel Motor Oil
For drivers of diesel powered vehicles, you will want to use a specific oil for diesel engines. Shell’s Rotella T6 synthetic oil is the best option and it can be used for regular diesel vehicles, classics, heavy duty trucks and even tractors.

In order to adhere to the latest emission standards, the Rotella formula made by Shell includes lower levels of ash, phosphorous and sulfur. By using this synthetic oil in your diesel motor, you may also notice a reduction in engine noise too.

Other features of the Shell Rotella T6 Engine Oil include:

  • 5W-40 oil
  • Low ash additives for reduced emissions
  • Improved engine wear performance and deposit control
  • Engineered with shear stability to resist viscosity loss
  • Improved fuel economy by up to 1.5%
  • Multiple sizes and bulk options available

If you are driving in extreme temperatures, the Rotella T6 uses a high viscosity level to improve the flow and provide protection against degradation. Overall, it’s the best synthetic motor oil for diesel engines that require a heavy duty synthetic blend.

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4. Pennzoil Ultra Platinum Full Synthetic Oil

Pennzoil Ultra Platinum Full Synthetic Oil
Pennzoil are a highly popular automotive brand in the USA and the Ultra Platinum is their most rated synthetic oil. It has been designed to deliver a faster low temperature oil flow as well as excellent protection against extreme heat. The brand also state on the bottle that it’s made from natural gases and the synthetic oil is also race trusted for complete peace of mind.

Other features of the Pennzoil Ultra Platinum Synthetic include:

  • 5W-20 oil
  • Delivers superior sludge protection
  • Oil stability and endurance during extreme conditions
  • Protects against viscosity loss and thermal breakdown
  • Ensures pistons are kept as clean as possible
  • Improved fuel economy
  • Wear and tear protection

The Pennzoil Ultra Platinum is an excellent all-rounder that promises improved responsiveness, smoothness and a quieter engine. It’s also a relatively affordable full synthetic oil that’s available in a 5 or 1 quart bottle size, which is great for keeping in the trunk and topping up when required.

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5. Royal Purple 51530 Performance Motor Oil

Royal Purple 51530 Performance Motor Oil
The Royal Purple 51530 is the best full synthetic oil for drivers looking for a high performance oil. It has a refined formula that’s been recently improved to increase power and enhance the smoothness for drivers of high powered vehicles.

For older and high mileage vehicles in particular, it can also help to reduce oil consumption as well as increase the lubrication inside of the engine.

Other features of the Royal Purple 51530 Performance include:

  • 5W-30 high performance oil
  • Superior corrosion protection additives
  • Increased fuel efficiency
  • Compatible with fuels containing ethanol
  • Improves emissions
  • Made in the USA and Dexos approved
  • Anti wear compound to prevent friction damage

Although the Royal Purple 51530 is slightly more expensive than many of the alternatives, it’s the best high performance motor oil. If you are driving your vehicle at “maximum attack” on the track, it’s vital that you are using a dedicated oil that protects and performs.

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6. Valvoline SynPower SAE 5W-30 Synthetic Oil

Valvoline SynPower SAE 5W-30 Synthetic Oil
The cheapest synthetic oil that’s highly rated is the Valvoline SynPower oil. The American owned and operated company have produced this oil to meet the regulations of the majority of cars manufactured in North America.

It’s designed to improve fuel efficiency, provide cold and high temperature protection, improve engine cleanliness and so much more.

Other features of the Valvoline SynPower Engine Oil include:

  • 5W-30 oil
  • Improves fuel efficiency
  • Made in the USA
  • Protection against sludge and varnish
  • Multiple viscosity ratings available
  • Bulk buy options

Overall, it’s one of the best synthetic oils for the money when compared against other premium motors oils that provide similar benefits. The brand also state that it provides “50% more wear protection” than their conventional oil alternative.

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7. AmazonBasics Full Synthetic Motor Oil

AmazonBasics Full Synthetic Motor Oil
AmazonBasics themselves provide their own full synthetic oil, which is available in multiple viscosity ratings. The brand also offer blends that include full synthetic, conventional and high mileage specific oils.

Although it’s one of the cheapest synthetic oils on the market, it has been approved by Dexos1 Gen 2, API SN Plus and ILSAC GF-5 for complete peace of mind.

Other features of the AmazonBasics Engine Oil include:

  • 5w-30 oil
  • Formulated for longer drain intervals
  • High resistance to viscosity and thermal breakdown
  • Minimizes engine deposits and exhaust emissions
  • Suitable for gasoline engines only
  • Improves fuel economy
  • High mileage full synthetic option

The AmazonBasics synthetic oil is an excellent all-round option that combines value for money and performance. There is also a variety of configurations to choose from such as viscosity and bottle sizes to best suit your requirement. The only drawback is that the bottle doesn’t have a transparent line on the side to view how much oil is left but this isn’t a major drawback.

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8. Liqui Moly 2041 Synthetic Oil

Liqui Moly 2041 Synthetic Oil
Liqui Moly are a highly reputable brand that are well-known for their premium oil additives. Their full synthetic motor oil follows their great reputation and is a SAE 5W-40 oil that’s available in multiple bottle sizes. The brand states that it provides instant lubrication after a cold start and even helps extend oil change intervals.

Other features of the Liqui Moly 2041 Engine Oil include:

  • 5w-40 oil
  • Made in Germany
  • Suitable for the latest engine concepts
  • Provides superior engine cleanliness
  • Rapid oil deliver at low temperatures
  • Enriched with premium additives
  • Long service life and great engine protection
  • Bulky buy options

The Liqui Moly 2041 is an excellent all-round synthetic oil but it does come with a premium price tag. However, the German made oil provides superior performance and is backed by the reputable brand for complete peace of mind.

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9. Castrol 03063 GTX MAGNATEC Full Synthetic

Castrol 03063 GTX MAGNATEC Full Synthetic
Another full synthetic motor oil by Castrol is the GTX MAGNATEC , which is suitable for gasoline engines. The formula is available as a 5W-20 or 5W-30 oil and is designed to cling onto critical parts to provide an added layer of protection.

The brand state that the intelligent molecules get to work instantly as soon as you start the engine. The protective layer that forms reduces engine wear and keeps the critical components up to four times smoother according to independent testing.

Other features of the Castrol GTX MAGNATEC include:

  • 5W-20 or 5W-30 viscosity
  • Fights against sludge build-up
  • 6x better wear protection
  • Ideal for severe driving conditions
  • Designed for gasoline engines
  • Dexos approved
  • Bulk buy options available

The Castrol GTX MAGNATEC is their most popular full synthetic oil that they produce and for good reason too. The superior engine protection and proven results make it an excellent all-round option that won’t disappoint.

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10. Motul 8100 X-cess Full Synthetic Oil

Motul 8100 X-cess Full Synthetic Oil
The Motul 9100 X-cess is a full synthetic oil that’s suitable for both gasoline or diesel engines. Motul are a highly reputable brand and they developed the first fully synthetic oil back in 1971, which should provide you with some confidence with this oil.

According to the brand, this motor oil works best when used with powerful or large displacement engines as it provides superior mechanical performance.

Other features of the Motul 9100 X-cess include:

  • 5W-40 viscosity rating
  • Maximum oil film resistance
  • High HTHS
  • Friction modifier for improved performance
  • Low volatility to reduce oil consumption
  • High sheer stability
  • Sold in 1.32 gallon bottles

Overall, the Motul 9100 X-cess is a highly rated full synthetic oil that’s ideal for performance engines. Although it’s fairly expensive when compared to the alternatives, it provides so many benefits that can transform the running of your engine.

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How We Rated The Synthetic Motor Oils

As we own a number of cars, we have plenty of experience using a whole range of different oils. Therefore, as well as our experience, we also based the recommendations within this article upon hours of research and a number of factors. The factors that we considered included their brand reputation, wear protection, value for money, viscosity availability, additional additives and bottle sizes.

Synthetic Oil Buying Guide

Motor oil is an essential component and it isn’t a luxury that you can simply ignore. Many car owners avoid servicing because it’s a cost that they would like to avoid. However, failing to service your car on a regular basis can result in a much larger repair bill later on as well as poor fuel economy.

Synthetic oils are seen as the best but some cars may require semi synthetic with lower ash ratings. Some motor oils are also formulated with a specific synthetic blends for high mileage cars whereas others are designed for cars used in cold weather. This is thanks to the various additives used within the formula and it’s the reason why there are so many synthetic motor oils to choose from.

To help you make an informed buying decision, we produced the below guide regarding synthetic motor oils.

best synthetic motor oil

Difference Between Conventional and Synthetic Oils?

Conventional oils are naturally occurring mineral based oils that are refined from crude oil. They are cheaper, protect the bare minimum of components and need to be changed more often.

Synthetic oils are fully man made oils, which is refined further in chemical plants. They provide maximum protection for the components of the engine and are able to withstand extreme temperatures. They cost more than conventional oils but are able to last longer and provides far greater protection.

Synthetic oil is available in two forms, which are semi synthetic and full synthetic. The main difference is that semi synthetic oils use both synthetic and mineral oils whereas full synthetic oil contains no mineral based oil. The synthetic blend of oil you choose is dependent upon the driving conditions and mileage of your vehicle.

Viscosity Grade

The viscosity of a motor oil basically refers to the oil’s resistance to flow and shear. The best way to describe viscosity is to imagine water and syrup, which are common household liquids. Water has a low viscosity grade whereas syrup has a much higher viscosity grade.

With that being said, you need to choose the correct viscosity grade for your motor. This will be listed in your car’s manual but you may choose a different oil based upon the type of driving you do, climate and the age of your vehicle.

For example, if you live in an area that’s below freezing most of the year, opting for a lower viscosity motor oil is recommended. However, if you are driving in high temperatures, involved in racing or haul heavy loads, you will want a higher viscosity motor oil.

The viscosity rating of the oil can be found on both the front and back of the bottle. The back of the bottle will also provide further details including the oil specification, which is shown in the image below in the black rectangle.

best Full Synthetic Oil

Oil Specification

Another rating you should check is the oil specification. The purpose of the specification is to determine the type of oil that’s suitable for the engine in order to provide optimum performance. All motor oils go through various independent industry testing to check that it meets the standard specification. Many brands such as Mobil 1 exceed these industry standards to ensure that your engine remains running like new.

How To Check Your Oil

Checking your oil is a very simple task that you should do at least once every 3 months or before any large road trips. To begin, park your car on level ground so that it doesn’t hinder the results. It’s advised that you perform this check with a cold engine so that you don’t burn yourself.

Open the hood and locate the dipstick, which should be clearly visible. Pull the dipstick out of the engine and clean the oil at the end. Once clean, place the dipstick back in and then pull it back out. Analyze both sides of the dipstick and check where the oil level is with regards to the dipstick measurement. Usually the indicator will be L to H, Min or Max or a cross hatching.

If the oil is no where to be seen, buy the correct oil for your car and pour it into the engine. If the oil level is correct, check the color of the oil. The correct oil color should be brown or black. If you notice any form of metal particles within the oil, this is a worrying sign that there is internal damage within the engine.

Although most synthetic motor oils are already packed with additives, many people may also use extra oil additives to help extend the life of the oil. It does this by altering the viscosity of the oil and ensuring that it’s not too thick or too thin.

How To Top Up Your Oil

If you need to top up your oil, you will firstly need to locate the oil filler cap, which usually has an “oil” marked on the lid or an icon of an oil can. To begin, start by placing a funnel over the top of the spout and pour the synthetic oil in. Check the dipstick to ensure that the oil level is correct after each half a quart.

It’s important to note that you should never overfill the engine with oil. Overfilling can cause damage, therefore it’s advised that you pour small amounts in and check the dipstick regularly. If you do accidentally overfill, you can use an oil extractor to remove the excess oil. If you find yourself regularly topping up your car with oil, this could indicate that your car is burning oil or there is an oil leak.

synthetic motor oil


Using a synthetic motor oil is essential for ensuring your car is running at its maximum performance and efficiency as well as protecting vital engine components.

Around a decade ago, there were only a few synthetic oils to choose from but now the variation can be quite confusing. However, hopefully our list of recommendations have narrowed down your search to make your choice that much easier. It’s important to note that you should also use a new oil filter when changing your car’s oil because this ensures all dirt and debris is filtered out of the engine.

procarreviews author

Written By Dan

About the Author

Dan is an automotive journalist and owner of over 10 cars ranging from supercars, tuned cars, classics and your good old beater cars. He always likes to get his hands dirty with nut and bolt restorations or detailing sessions using the best products on the market.

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