What Is The Best Synthetic Oil? (2021 Edition)

Best Synthetic Motor Oil - Featured Image

Without the right kind of oil, your car will suffer from poor performance and an increased risk of potential engine failure. Most modern cars do best when given full synthetic oils.

But finding the best synthetic oil can be confusing. What type, weight and viscosity of oil is best for your specific car? Don’t worry if you’re not sure – our complete guide to the best synthetic oil is here to help. Check out our top 10 recommendations for the best synthetic motor oil brand of 2021, as well as answers to common oil questions:

On your mark, get set and let’s go!

Synthetic Motor Oil Reviews

Our #1 Choice
Castrol 03084C Edge 5W-30 Advanced Full Synthetic Motor Oil, 5 Quart
Pennzoil Platinum Full Synthetic 5W-20 Motor Oil (1-Quart, Case of 6)
Honorable Mention
Valvoline Advanced Full Synthetic SAE 5W-30 Motor Oil 5 QT (Packaging May Vary)
Castrol 03084C Edge 5W-30 Advanced Full Synthetic Motor Oil, 5 Quart
Pennzoil Platinum Full Synthetic 5W-20 Motor Oil (1-Quart, Case of 6)
Valvoline Advanced Full Synthetic SAE 5W-30 Motor Oil 5 QT (Packaging May Vary)
Our #1 Choice
Castrol 03084C Edge 5W-30 Advanced Full Synthetic Motor Oil, 5 Quart
Castrol 03084C Edge 5W-30 Advanced Full Synthetic Motor Oil, 5 Quart
Pennzoil Platinum Full Synthetic 5W-20 Motor Oil (1-Quart, Case of 6)
Pennzoil Platinum Full Synthetic 5W-20 Motor Oil (1-Quart, Case of 6)
Honorable Mention
Valvoline Advanced Full Synthetic SAE 5W-30 Motor Oil 5 QT (Packaging May Vary)
Valvoline Advanced Full Synthetic SAE 5W-30 Motor Oil 5 QT (Packaging May Vary)

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

This is Castrol’s most advanced full synthetic oil designed to avoid metal-to-metal contact during all levels of driving speeds.


  • Designed for high-performance vehicles
  • Suitable for professional racing
  • Metal-to-metal lubrication protects engine from long-term damage
  • Protects against viscosity breakdown


  • Might not be the most effective choice for engines over 30 years

Castrol Edge Motor Oil is a favorite among top-performing racecar teams as well as everyday drivers around the world. The 03084 EDGE is their premier oil engineered with fluid titanium technology. This allows the oil to avoid viscosity breakdown even at high-performance levels.

This is an oil created specifically for modern, high-powered engines, which are roughly twice the size of engines built just 30 years ago. This is the best synthetic motor oil for large engines that have the potential for harmful metal-to-metal contact. Castrol EDGE motor oil is designed to provide lubrication across the engine for the entire drain interval.

2. Pennzoil Platinum Full Synthetic

While all fully synthetic motor oils help reduce engine sludge, Pennzoil Fully Synthetic Motor Oil uses Super Active Cleaning Agents to specifically target and remove intense sludge buildup.


  • Trusted Pennzoil brand with satisfaction guarantee
  • Quick and efficient way to remove buildup
  • Protect engine in extreme low or high temperatures


  • Cap must be replaced tightly or leaks can occur
  • Expiration date can be relatively short

Conventional oil can break down and cause sludge buildup, which can slow or even stop your engine. Pennzoil 550022686 uses unique Cleansing Agents to remove this buildup quickly. Not only meets all industry requirements for cleanliness but actually exceeds them quite significantly.

This oil is also a great choice for harsh weather including both hot and low temperatures. Formulated to help protect your engine from damage due to excessive humidity, heat and water exposure.

3. Valvoline SynPower 5W-30 Full Synthetic Motor Oil

Certified for use in practically all major turbo and supercharged passenger cars in North America, Valvoline SynPower 5W-30 cleans the engine while delivering maximum performance.


  • Free customer support for all customers
  • Designed for high-performance vehicles
  • Protects against weather and environmental damage


  • Redesigned container can be difficult to handle and pour

Valvoline understands that because their oil is designed to last long, you might have a question about usage well after you’ve purchased the product. So they offer a dedicated customer support line at 1-800-TEAM-VAL to provide answer to any product or technical questions about their oil.

But most people have absolutely no problems with the SynPower line of oil. This is Valvoline’s high-performance oil designed for virtually all high performing passenger cars on the market. Plus, the oil also removes sludge while protecting varnish. Keeps the engine running smoothly even in harsh weather and low or high temperatures. Allows for an average of 10,000 miles between oil changes.

4. Shell ROTELLA T6 Full Synthetic Diesel Engine Oil

A heavy-duty engine oil which improves fuel economy while also providing plenty of protection to diesel engines.


  • Additives specifically designed for heavy-duty diesel engines
  • Improves fuel economy by 1.5%
  • Helps protect engine against harsh environmental conditions


  • Only suitable for diesel-powered vehicles

Heavy-duty diesel pickups, tractor-trailers and other diesel-powered vehicles also benefit from full synthetic oil, and Shell ROTELLA T6 Diesel Engine Oil is specifically formulated for their unique demands. The Triple Protection Plus formula helps prevent damage from dirt, soot and other environmental hazards unique to heavy-duty diesel vehicles.

Additionally, this Shell ROTELLA synthetic oil improves overall fuel economy by 1.5% compared to other SAE 15W-40 motor oils. After all, every bit of fuel economy savings helps. Also helps maintain optimal engine pressure even under stressful, hard-working conditions.

5. Liqui Moly 2041 Premium 5W-40 Synthetic Oil

Liqui Moly is a versatile synthetic oil designed to help conserve energy while also delivering high performance in both hot and low temperatures.


  • Noticeable reduction in idle noise
  • Designed for both gas and diesel engines
  • Trusted brand named used by mechanics and other professionals


  • Similar packaging of different grades can be confusing

Liqui Moly doesn’t have the name recognition of the other best synthetic oils on our list, but they remain a consistent favorite of both professional and D.I.Y. mechanics around the world. Their High Tech 5W-40 Motor Oil is a full synthetic oil suitable for both gas and diesel engine concepts.

The oil is also designed for multi-valve arrangements, variable cam and time configurations, turbocharging, supercharging and other high-performance situations. Provides instant lubrication after a cold start, making it perfect for use in all types of extreme climates. Ideal for cars which are driven everyday as well as cars you’ll want to safely store for an extended period of time.

6. Mobil 1 Extended Performance 5W-30

This synthetic oil from a well-known brand performs excellently at both hot and cold temperatures, and it offers long term protection.


  • Extended protection thanks to its viscosity and lubrication properties.
  • Superior performance at both cold and hot temperatures. You can use the same oil regardless of the season, and you do not have to get an oil change for the next season.
  • Comes from a reputable brand. Mobil is a favorite of mechanics, and it is the official oil of NASCAR.


  • Mobil 1 Extended Performance 5W-30 is one of the more-expensive synthetic oil brands on the market.
  • Some buyers complain that the bottles contain leaks.

Mobil 1 Extended Performance 5W-30 provides excellent protection at different temperature levels. Its formulation makes it an ideal synthetic blend oil for cold weather, but you can also rely on it in hot conditions as well.

In addition to advanced lubricative properties, this oil provides a long interval between changes because it can protect for longer than the average oil. You should always still change your oil ontime, but if you go past the regular change interval, this synthetic oil can continue to provide protection.

7. Valvoline MaxLIfe High Mileage 5W-30

Valvoline created the formula for this synthetic blend oil for use in older vehicles.


  • Specially formulated for use in older vehicles, MaxLife High Mileage 5W-30 provides engine wear protection.
  • This oil helps prevent sludge buildup and protects against leaks.
  • The formula includes anti-oxidation compounds that protect against rust and other problems that can destroy older engines.
  • The price tag for this oil is quite reasonable by synthetic oil standards.


  • Valvoline Max LIfe High-Mileage 5W-30 is not for use in newer vehicles.
  • The oil needs to get changed more frequently than some other best synthetic oils.

Valvoline MaxLIfe High-Mileage 5W-30 is specifically for use in older engines. It performs well in vehicles that have more than 75,000 miles on them. If you own one of these older cars, then longevity is likely very essential to you.

The MaxLife High Mileage oil helps prevent oil sludge buildup, and it aids in the prevention of oil leaks, which are a common problem in older vehicles. The drawback, of course, is that the oil is not meant for newer vehicles. However, the oil comes with a cheaper price tag, so you can enjoy the benefits of sludge and leak protection without the higher price tag usually associated with synthetic oils.

8. Royal Purple 51530 API-Licensed SAE 5W-30

This oil is a favorite choice of high performance vehicle owners.


  • The Royal Purple 51530 API-Licensed SAE 5W-30 improves fuel efficiency.
  • It also offers superior protection against corrosion.
  • Users get to enjoy an extended change interval.
  • Royal Purple specially forumates this oil for use with high performance vehicles.


  • The Royal Purple 51530 API-Licensed SAE 5W-30 has a higher price tag that some other synthetic oil options.
  • Users who do not have high performance cars may not need all the benefits that this oil provides.

Royal Purple 51530 API-Licensed SAE 5W-30 is popular with drivers of sports cars and other performance-oriented vehicles. Even so, it has some practical attributes. One of the most important is that it is fully-compatible with other synthetic oils, so you do not need to do anything special when switching from or to another oil.

This Royal Purple product also provides excellent protection against corrosion. Like other premium synthetic oils, this one allows you to extend the interval between oil changes. It also has properties that maximize fuel efficiency and enhance performance.

9. Castrol GTX High-Mileage Oil

This reasonably-priced synthetic oil provides protection for older vehicles.


  • Castrol GTX High-Mileage Oil provides superior protection for cars with high mileage up to 150,000 miles or more on their odometers.
  • The oil protects against sludge buildup and corrosion.
  • The oil is on the lower end of the price range for synthetic oils.


  • This oil is not for newer vehicles, and there may be better choices for vehicles with high mileage up to 100,000 miles on them.

This synthetic oil is for cars that have high mileage over 100,000 miles, and some users say that GTX high-mileage oil performs its best on engines that have high mileage more than 150,000 miles on them. The formula resists burnoff, which is a problem in older engines.

Its viscosity grade does not break down as rapidly as other motor oils, so its lubricating properties remain for the whole change interval. GTX high mileage oils also help deal with other issues associated with older engines, such as sludge buildup, corrosion, and rust.

10. Valvoline VR 1 Racing Oil

This oil works for high-performance sports cars and can also provide benefits for daily commuters.


  • Valvoline VR 1 Racing Oil offers exceptional anti-wear properties that keep high-performance engines running at their peak.
  • The oil does not burn off thanks to the burn resistant compounds in its formula.
  • The formula includes zinc, which protects against both engine wear and corrosion.
  • This oil has enough high-performance properties to make it a favorite of race car drivers.


  • This oil performs well in newer vehicles, but it is not the best option for older cars.
  • Some economy cars may not need the performance benefits that this oil provides.
  • This oil is at the higher end of the synthetic oil price spectrum.

Valvoline VR 1 Racing Oil is a high-performance oil that offers superior engine wear protection and helps cars achieve their maximum amount of horsepower. This oil, as its name suggests, is a favorite of weekend race enthusiasts, but sports car owners and regular commuters with higher-horsepower cars may also like this product.

Frequently Asked Questions

Here are the answers to some common questions about buying and using the best synthetic oil. Remember to also consult your owner’s manual (if you don’t have a physical copy, check out the car manufacturers’ official website). Manufacturer’s recommendations on the type of oil, frequency of oil changes and more are all specifically designed to deliver top performance and safe operation for your specific vehicle.

What is Synthetic Oil?

Oil is divided into two types: synthetic and conventional.

Synthetic oil is chemically engineered to be a pure lubricant. These oils are contaminant-free, with every single molecule designed to promote lubrication. Because they’re lab-engineered, they’re made without impurities. Their internal molecular structure is uniform with no discrepancies.

Conventional oils (also called standard motor oil) is refined from crude oil. The refining process for crude oil is different than the one for synthetic oil. Molecules in conventional oils will have similar weight but differing structures, which affects performance. Additionally, conventional oils will always have at least a low level of contaminants such as sulfur, nitrogen, oxygen, nickel and vanadium.

What are the Advantages of Synthetic Oil?

Generally, most experts agree that full synthetic oil is usually the best option for most modern cars. Full synthetic oil has no contaminants or impurities, so there’s less friction on the engine.

Synthetic oil also helps increase fuel efficiency. Plus, synthetic oil helps protect your car from damage caused by both extreme temperatures.

What are the Disadvantages of Synthetic Oil?

The main disadvantage is cost. Synthetic oil is often anywhere from two to four times the cost of conventional motor oil. However, the price difference is not quite as clear-cut as it might first seem.

Synthetic oil lasts about three times as long as conventional oil. By using synthetic oils, you don’t have to change your oil nearly as often each year. While specific results will vary, you could be looking at using anywhere between 15 to 24 fewer quarts of oil each year.

So conventional oil is really only a savings at the checkout counter. Because you have to change synthetic oil less, you don’t have to buy it as often. So, for most drivers, conventional oil is actually the best value over time.

Who Should Use Synthetic Oil?

Full synthetic oil is often the best choice for the average driver in a modern car. However, there are also a few specific situations where synthetic oil is not just the best choice, but really the only workable one:

Cars in Extreme Climates

Use synthetic oil if you drive your car in either consistently cold or high temperatures.

Synthetic oil can operate normally in a very high temperature range than conventional oil. Remember, the temperature inside your running engine is much hotter than the outside temperature. If you frequently drive in areas where the outside air is 70 degrees or higher, conventional oil could break down and cause engine damage.

Synthetic oil is the best choice for cold temperatures, too. Conventional oil typically doesn’t provide enough engine protection against engine wear during cold-temperature startup. Only synthetic oil can keep your engine flowing in frigid temps, especially below zero conditions.

Cars Used for Towing and Hauling

Synthetic oil won’t break down as quickly under heavy engine strain. If you’ll be towing a car, pulling a trailer or otherwise hauling cargo, make sure you’re using synthetic oil. Standard oil might not be able to provide enough lubrication for engine components operating under maximum power.

Older Engines Which Need Sludge Removal

Older engines have an increased risk of sludge buildup. If too much gunky residue is allowed to accumulate through the engine, oil passages can be blocked and extensive damage can occur. Oil sludge is caused by oil breakdown over time. This was an especially pronounced problem in Chryslers, Toyotas and Volkswagens in the early 2000s.

Regular use of synthetic oil helps remove existing oil sludge. Plus, synthetic oil helps prevent new sludge from building up in the future.

Cars Which Make Frequent Short Trips

You’ll definitely want to use synthetic oil if your daily driving consists of lots of short trips, stop-and-go traffic and similar conditions. Conventional oil needs time to warm up in order to burn off impurities and moisture. Short trips don’t allow enough time for the conventional oil to warm up to the proper temperatures, so oil breakdown occurs relatively quickly.

Synthetic oil warms up faster. Plus, synthetic oil doesn’t contain any impurities to begin with. So it’s able to lubricate longer and won’t potentially cause engine damage.

How Often Should Synthetic Oil Be Changed?

A very general rule you’re like to hear is the “3 or 3” rule. You should do an oil change either every three months or every three thousand miles. While there’s nothing wrong with following that guideline – you certainly won’t harm your car doing so – many vehicles don’t require such a frequent oil change.

Depending on the type of vehicle, average driving conditions and type of synthetic oil used, your vehicle might need an oil change every 10, 15 or 20,000 miles. This could mean you only need to change your oil every six months or even just once a year. As always, consult your owner’s manual for specific details.

While synthetic oil is long-lasting, don’t overestimate its abilities. Regular oil changes are still an important part in the safe operation of your vehicle. Never ignore any warning lights or another onboard vehicle indicators.

What’s the Best Type of Synthetic Oil?

Not all synthetic oils are the same. Because these are engineered oils, the manufacturing process can make a big difference in the quality of the oil. You’ll want a trusted manufacturer with rigorous quality control standards.

You’ll need to select the right viscosity grade for your car’s engine. Viscosity is the term for the oil’s thickness. If the oil is too thick or too thin, it won’t be able to adequately protect your car’s engine, which can result in damage.

Most manufacturers provide two different viscosity recommendations. The main recommendation is what will be the absolute best choice for maximum protection and performance. The other recommendation is called an alternate-weight oil. While not as ideal as the first oil, the alternate-weight can be safely used when the first type isn’t available.

Obviously, nobody can just look at an oil and determine its quality. But quality oil will make it known they comply with different industry standards. The two main certifications you want to look for are the:

Certification should usually be pretty easy to find right on the oil container. Only synthetic oil can meet these standards, so you won’t find any conventional oils certified by the SAE and API.

Be careful about any synthetic oil which is certified by an organization besides the SAE and API. Some lower quality synthetic motor oils create their own official-sounding organizations to then certify their own oil. These synthetic motor oils will likely be brands you’ve never heard of at prices which are a bit too good to be true.

Is Synthetic Oil Good for the Environment?

Many people assume that because synthetic oils aren’t refined from petroleum, they’re safer for the environment. Unfortunately, that’s not necessarily the case. The process used to make synthetic oil still releases environmentally-damaging chemicals.

However, synthetic oil does have some environmental benefits. Synthetic oil makes the engine run cleaner. Plus, the lower volatility of synthetic oil results in less vaporization throughout the exhaust. Synthetic oil decreases engine resistance while increasing horsepower, which means the car needs less gas to perform at a high level.

How Does Oil Provide Wear Protection for Your Engine?

Oil provides wear protection for your engine. All motor oils have lubricating qualities, and synthetic motor oil enhances these natural properties. In other words, quality synthetic oils can provide better lubrication than non synthetic alternatives.

You need to change oil when it starts to lose these wear protection properties. This reason is why changing oil at regular intervals is so important. Quality synthetic oils can extend the change interval because they protect against wear for more extended periods than conventional motor oil.

Furthermore, the type of wear protection can be more specialized because synthetic oil can have very specific additives that address particular issues. For example, motor oils have formulas that work best on older vehicles, others are for high-performance cars, and others work best at very cold temperatures.

Wear occurs when engine parts rub against one another during operation. Oil lubricates the parts to keep them separate so that this wear-producing rubbing does not occur. The best synthetic oils are able to perform under a wide range of conditions. For example, a premium synthetic or synthetic blend oil can provide the necessary lubrication in very cold or very high temperatures.

Synthetic blend oil formulas also often include additional compounds that protect against rust and corrosion, prevent sludge buildup. These benefits are not the main reason to get synthetic oil, but they are critical to the performance and longevity of your engine.

Can Synthetic Oil Help Improve Fuel Efficiency?

Clean engine oil can help a car improve its fuel economy. Generally, sludgy oil that does not lubricate properly causes an engine to run hotter and less efficiently. When an engine is in this condition, the car uses more fuel because it is harder for it to operate. In a sense, the engine needs more power to push through the sludge and deal with the extra friction from improper lubrication.

Synthetic engine oil provides better performance, so you can go for an extended amount of time between oil changes. Also, some synthetic formulas include compounds that fight against corrosion and other issues that can shorten the life of an engine.

Not only does clean oil help engines reach their fuel economy peak, but these products can also improve performance by helping engines operate at the ideal condition.

Can the Right Synthetic Oil Actually Improve Engine Performance?

Motor oils often claim that they can improve performance. These products do not actually increase the horsepower of your engine. However, they can help it operate at its absolute peak. If you are concerned about engine performance, then you need your engine to perform at its peak in all sorts of conditions, at different speeds, or for long periods such as during an extended road trip.

Premium full synthetic oils are specifically for these high-stress situations, and they can indeed ensure that your car gets the maximum amount of horsepower without causing wear to the engine components. They do this by offering superior lubrication while the engine is running at higher speeds.

Does Synthetic Motor Oil Provide Engine Protection?

Conventional oil and synthetic oil are both motor oils. However, synthetic oil is an oil base with different additives. In other words, companies that produce full synthetic oil refine it much more than conventional oil.

The additives in full synthetic oil allow it to provide better protection than conventional oil. First of all, the extra refining often focuses on improving the lubricating properties of the oil.

Final Thoughts

Oil is the lifeblood of your vehicle. The right oil will dramatically improve your vehicle’s performance and fuel efficiency while decreasing environmental impact and risk of engine damage.

While many cars allow for both conventional and full synthetic oil, most drivers prefer the benefits of full synthetic. Full synthetic oil is usually the most cost-effective, reliable solution suitable for the widest range of weather and driving conditions.

Using our guide above, you’ll be able to choose the best synthetic motor oil for your needs. A whole new world of adventures awaits you on the road today!

Brett Gordon

The engine behind editing at DigMyRide and the brains behind its build. During the day, Brett is a thirty-something dude from SoCal climbing the corporate ladder, but by night, he spends his time contributing to the online world of automotive tech & trends.