Best Full Synthetic Motor Oil(And How To Choose The Right Oil For Your Car )

The Best Fully synthetic Motor oils prices as of  2021-09-24 at 03:46 UTC Details

If you are planning on changing the oil in your car soon, then go check out my favourite synthetic oil, Castrol Magnatec GTX Synthetic Oil. It is, in my opinion, one of the best all round synthetic oils for petrol or diesel engines.

In this article, I’ll run through my top 7 favorite synthetic oils, and I’ll explain how to choose the best oil for your car or truck, and what you need to look out for when it comes to choosing between oil types and specifications.

Fully Synthetic Engine Oil – Detailed Reviews

1. Castrol GTX Magnatec 5W-30 Synthetic Oil

Best Synthetic Oil’ prices as of  2021-09-24 at 02:54 UTC Details

Main Features
  • Ultimate protection of critical engine parts
  • Instant protection from the moment you start the engine
  • Best value for your money

When it comes to the Best Synthetic Engine Oil in the market, Castrol GTX MAGNATEC 5W-30 is, in our opinion, the hands down winner. This product not only has all the bells and whistles you can expect from a fully synthetic engine oil but it usually can be found at an unbeatable price, sometimes half the price of it’s competitors.

What Engines Can Use It?

This Castrol synthetic oil can be used on any modern gasoline engine, however, it’s especially suited for petrol, direct injection engines including but not limited to Gasoline Direct Injection (GDI), Fuel Injection System (FIS), Spark Ignited Direct Injection (SIDI), and Ford EcoBoost.

That said, this top performer engine oil complies with GM dexos1 Gen 2 specification as well as Ford’s newest engine oil specifications making it ideal for any modern GM or Ford vehicle, even during its warranty period.

What Makes It Different?

Castrol’s intelligent clinging molecules formula adds an extra layer of protection to your engine even during cold starts. This translates into a dramatic decrease in engine wear and better fuel economy.

Approvals & Specifications

The following are the official specifications and OEM approvals for this oil, please compare this information with your owner’s manual recommendations before buying the product.

  • API SN Plus/SN
  • ILSAC GF-5
  • GM dexos1® Gen 2
  • Ford WSS M2C929-A, WSS M2C946-A
  • Dramatically reduces engine wear
  • Enhances fuel efficiency
  • Instant protection during cold start
  • Intelligent clinging molecules formula
  • This variant of Castrol GTX is only available for petrol engines

Click Here To Learn More About Castrol GTX Synthetic Oil On Amazon

2. Shell Rotella T6 5W-40 Synthetic Oil prices as of  2021-09-24 at 02:54 UTC Details

Main Features
  • Better Fuel Economy
  • Improved Wear Performance
  • Excellent Deposit Control

Diesel engines are known for their endurance, heavy duty build quality, and durability. Shell ROTELLA T6 5W-40 stands for all those attributes and some more. If you are looking for the best synthetic oil for diesel engines then look no further, this one is definitely worth checking out.

What Engines Can Use It?

This is a synthetic oil you can use on literally any diesel engine, ranging from off-highway heavy-duty applications to cars and even motorcycles. It’s improved resistance to breakdown by high temperatures makes it ideal for all applications.

What Makes It Different?

Shell’s exclusive triple protection formula adds a huge barrier against corrosion from acids, deposits, dirt, and other contaminants. Besides its superior wear protection, the Shell ROTELLA T6 formula is also emissions system friendly, offers an outstanding shear stability in any weather condition and benefit fuel economy.

Approvals & Specifications

The following are the official specifications and OEM approvals for this oil, please compare this information with your owner’s manual recommendations before buying the product.

  • API: CK-4, CJ-4, CI-4 PLUS, CI-4, CH-4
  • ACEA E9; JASO DH-2; Cummins CES 20086; Volvo VDS-4.5; Detroit Fluid Specification (DFS) 93K222, Caterpillar ECF-2/ECF-3, MAN M3575, JASO MA/MA2, Allison TES 439, MB-Approval 228.31
  • Superior engine protection
  • Better fuel efficiency
  • Outstanding heat resistance
  • All weather Oil
  • Triple protection formula
  • Only suitable for diesel engines

Click Here To Learn More Shell Rotella T6 On Amazon

3. Valvoline Synpower 0W-20 prices as of  2021-09-24 at 03:46 UTC Details

Main Features
  • Outstanding properties in cold weather
  • Superior protection
  • Can be used on any kind of engine

The Valvoline SYNPOWER 0W-20 is in our opinion one of the best all-around synthetic oils available for winter and cold climates. It not only satisfies the latest industry standards, but also its ultra-low viscosity guarantees an instant oil flow under the most extreme low-temperature conditions.

What Engines Can Use It?

Basically, any engine can use this Valvoline full synthetic oil. This superior synthetic engine oil is formulated for passenger cars with petrol, diesel, LGP or even Hybrid engines. Its has an astounding operating range of -45°C to 236°C,  making it worthy of being called the best synthetic oil for cold climates. However, due to its low viscosity, this oil is definitely not suited for vehicles operating in hot climates, high mileage engines or severe driving conditions. 

What Makes It Different?

Valvoline SYNPOWER 0W-20 is designed to provide extra protection under low-temperature conditions. It cointains special additives that prevent the formation of sludge, varnishes, and other harmful deposits. The “instant flow” during cold starts also helps the fuel economy and protects against engine wear.

Approvals & Specifications

The following are the official specifications and OEM approvals for this oil, please compare this information with your owner’s manual recommendations before buying the product.

  • API: SN-RC
  • Chrysler MS 6395
  • Ford WSS-M2C947-A
  • ILSAC GF-5
  • Ultimate low-temperature protection
  • Suited to all kinds of engines
  • Special additives that keep the engine clean
  • Not recommended for high mileage engines, severe driving conditions or warm climates

Click Here To Learn More About Valvoline Synpower Synthetic Oil On Amazon

4. Castrol Edge Extended Performance 5W-30 prices as of  2021-09-24 at 03:46 UTC Details

Main Features
  • Extended service intervals
  • Ultimate protection against wear
  • Enhanced fuel economy

The general rule of thumb recommends that synthetic engine oil should be changed every 7,500 or 10,000 miles. Why not 15,000 miles? That’s precisely what Castrol EDGE Extended Performance 5W-30 brings to the table, extended oil change intervals.

What Engines Can Use It?

WARNING: if your vehicle is under warranty or is used under severe conditions such as racing, frequent towing, commercial use, excessive idling, or dusty conditions then only follow the oil change interval recommended by your car manufacturer.

You can think of Castrol EDGE Extended Performance as Castrol GTX MAGNATEC on steroids. Ok so they are different oils with a different formula, but from a pragmatic point of view, both oils have quite similar applications. Almost any petrol engine can use Castrol EDGE synthetic oil, though the convenience of enjoying extended maintenance periods will depend on the use of the vehicle. 

What Makes It Different?

The selling point of this oil from Castrol, is the longer service intervals. In order to make possible such a difficult task, Castrol uses a special additive called: Titanium FST. The gains on performance, power, fuel economy and protection are noticeable as you can expect from a premium product.

Approvals & Specifications

The following are the official specifications and OEM approvals for this oil, please compare this information with your owner’s manual recommendations before buying the product.

  • API: SN, SM, SL, SJ
  • ILSAC GF-5, GF-4, GF-3
  • ACEA A1/B1
  • Chrysler MS-6395
  • Ford WSS-M2C153-H, WSS-M2C929-A, WSS-M2C930-A, WSS-M2C945-A, WSS-M2C946-A
  • GM 4718M, 6094M, dexos1, LL-A-025
  • Honda HTO-06
  • Extended oil change intervals
  • Fluid Titanium FST
  • Ultimate protection during cold starts
  • Better fuel economy
  • Usually more expensive than average synthetic oils
  • This variant is only suitable for petrol engines

Click Here To Learn More About Castrol Edge Extended Performance Oil On Amazon

5. Pennzoil Ultra Platinum 5W-30 prices as of  2021-09-24 at 03:46 UTC Details

Main Features
  • Better Fuel Economy
  • Excellent protection during severe driving conditions
  • Unsurpassed cleaning agents

If your driving routine consists of frequent stop-and-go traffic, short trips, heavy loads, off-road or dusty conditions then Pennzoil 5W30 is going to be a great option for your car. This premium synthetic engine oil is designed with severe driving conditions in mind as well as enhanced fuel economy.

What Engines Can Use It?

This Pennzoil platinum 5w30 oil comes with a huge number of OEM and industry approvals. If your car uses a petrol or even a diesel engine, chances are that Pennzoil Ultra Platinum 5W-30 has it covered. 

What Makes It Different?

This particular synthetic oil focuses on better fuel economy, superior wear protection, and excellent oil flow during low and high temperatures. Although what really makes it special is its PurePlus technology that excels at protecting the engine during extreme conditions.

In fact, Hennessey Performance vehicles, and SRT engines recommend using this oil for racing applications which gives you an idea about its quality, especially during harsh driving conditions.

Approvals & Specifications

The following are the official specifications and OEM approvals for this oil, please compare this information with your owner’s manual recommendations before buying the product.

  • API: SN, SM, SJ
  • ILSAC GF-5
  • ACEA A5/B5-10, A5/B5-12
  • Chrysler MS-6395
  • Ford WSS-M2C947-A, WSS-M2C929-A, WSS-M2C930-A, WSS-M2C945-A, WSS-M2C946-A
  • GM 6094M, 4718M, dexos1
  • Honda HTO-06
  • Excellent for severe driving conditions
  • Contains cleaning agents
  • Can sometimes improve fuel economy

Click Here To Learn More About Penzzoil Ultra Platinum Synthetic Oil On Amazon

6. Motul X-cess 5W-40 Synthetic Oil prices as of  2021-09-24 at 02:54 UTC Details

Main Features
  • Ultimate performance oil for high performance applications
  • Excellent for severe driving conditions
  • Unsurpassed anti-wear protection

This roundup wouldn’t be complete without including a category for high-performance engines. In our opinion, this is one of the best synthetic engine oils when it comes to high power engines.

What Engines Can Use It?

The MOTUL X-cess 5W-40 is intended for high-performance petrol, LPG or diesel engines. It is recommended by manufacturers such as Porsche, BMW, Opel, and Mercedes Benz for many of their engines. This is not a synthetic oil for normal vehicles, although you can use it if you are willing to pay its premium price.

What Makes It Different?

Ultra high-performance engines demand very specific properties. The Porsche A40 standard for example requires extreme high shear resistance from the lubricant. The BMW Long Life-01 specification demands severe constraints to the oil you can use due to the BMW Valvetronic system. MOTUL X-cess 5W-40 is a better synthetic oil because it complies with the most extreme OEM requirements.

Approvals & Specifications

The following are the official specifications and OEM approvals for this oil, please compare this information with your owner’s manual recommendations before buying the product.

  • API: SN, CF
  • ACEA A3/B4
  • BMW LL-01
  • MB-Approval 229.5
  • Porsche A40
  • Renault RN0700
  • Renault RN0710
  • VW 502 00 – 505 00
  • GM-Opel LL B-025
  • FIAT 9.55535-H2, FIAT 9.55535-M2, FIAT 9.55535-N2
  • Excellent for severe driving conditions
  • Ultimate high-performance engine oil
  • Best protection for high-tech engines
  • Usually more expensive than standard synthetic oils

Click Here To Learn More About Motul X-cess 5W-40 On Amazon

7. Mobil 1 High Mileage 5W-30 Synthetic Oil prices as of  2021-09-24 at 02:54 UTC Details

Main Features
  • Unsurpassed protection for high mileage engines
  • Excellent wear protection
  • Can help reduce oil leaks

Over time, engines inevitably suffer from internal wear. Traditionally, the way to compensate it was using higher viscosity oils. Nowadays products like the Mobil 1 High Mileage 5W-30 are specially designed to cover all the unique needs of high mileage engines.

What Engines Can Use It?

As you may guess, this oil from Mobil is geared toward engines with more than 75,000 miles, including engines that have in the past used lower quality oils. That said, Mobil 1 High Mileage synthetic oil is an excellent quality oil, with many manufacturer certifications making it a perfect choice for almost any petrol engine.

What Makes It Different?

Mobil uses a proprietary formula and special additives designed to provide the best protection against wear, excessive deposits and also extend the engine life. But benefits don’t end there, its formula also contains seal conditioners that can help to block existing and future leaks. 

Approvals & Specifications

The following are the official specifications and OEM approvals for this oil, please compare this information with your owner’s manual recommendations before buying the product.

  • API: CF, SL, SM, SN, SN Plus
  • ACEA A1/B1, A5/B5
  • Ideal for high mileage engines
  • Can help prevent oil leaks
  • Can extend the life of higher mileage engines
  • Not suited to new engines

Click Here To Learn More About Mobil 1 High Mileage Synthetic Oil On Amazon

Synthetic Motor Oil Buying Guide

As automotive technology advances and new engines are introduced the importance of using the top synthetic engine oil becomes more important. So, what is the best synthetic oil? 

Modern vehicles are designed with specific lubricants in mind. The engine oil is probably the most crucial lubricant in your engine, and should be checked and changed regularly.

Overlooking the original equipment manufacturer (OEM) recommendations is not a good idea, and engine oil change intervals should always be followed. Marketing is not a good adviser when it comes to choosing the right oil specification . So our first tip is taking a picture of your vehicle engine oil specifications and ensure the oil you choose matches them exactly.

check engine oil

It’s important to regularly check the engine oil level and top it up between oil changes

Most of the differences between the oils we have reviewed here are in the additives that engine oil manufacturers include in the oil mix. It’s important to note that no matter what brand of oil you choose, the  weight and viscosity of the oil is the most important specification. Choosing the wrong spec oil can damage your engine.

For now, don’t worry about the technical jargon and the numbers. The sections below will explain everything you need to know.

What Type Of Engine Oil Do I Need?

Mineral oil is the most common and older type of engine oil. In its most basic form, mineral oil is created from refined crude oil, also known as mineral oil base. In the later stages of the process, certain additives are combined with the oil base to improve its properties, notably its viscosity.

So, what is Synthetic Oil?

On the other hand, a fully synthetic engine oil is created from artificially designed compounds rather than using a petroleum base. However, nowadays there is a debate about the term “fully synthetic” since some brands are creating synthetic oil from chemically altered mineral oil bases and still calling it fully synthetic. Controversy aside, let’s accept the synthetic oil designation as an artificially enhanced engine oil.

best synthetic engine oil

Choosing the right engine oil can be confusing

There is currently another kind of engine oil called semi-synthetic or simply “blend”. As you may suspect this is not a 100% synthetic oil.

Synthetic blend engine oil is about 80% mineral base oil with 20% added synthetic components. This type of oil aims to offer the benefits of synthetic oil at a lower price point.

The Differences Between  Engine Oil Types – Fully Synthetic, Semi-Synthetic or Mineral Engine Oil?

The best way to understand why synthetic oil is your best option is to compare it to traditional mineral oil:

Synthetic Engine Oil

Traditional Mineral Oil

Preserves its viscosity over time

Becomes thicker over time

Longer service intervals

Requires shorter service intervals

Offer better performance in extreme cold or extreme heat conditions

Are susceptible to lose its properties under extreme temperature conditions

Better fuel economy

Lower fuel economy

Provides better lubrication thus prolonging engine life

Average engine lubrication, 

Use higher quality additives for improving oil properties and benefits

Use additives mostly to prevent its degradation

What about the synthetic blend? Depending on your engine specifications you may use a semi-synthetic engine oil and obtain most of the fully synthetic benefits.

Engine Oil Specifications

The most widely cited specification of engine oil is the Society of Automotive Engineers (SAE) viscosity grade. In simple terms, the SAE viscosity is composed of two numbers, the first one is an indication of oil viscosity at low temperatures (winter) and the second one at high temperatures. 

Confused? Don’t worry, just check the following cheat sheet:

Synthetic Engine Oil

SAE grade

Outside Temperature Range

Valvoline SYNPOW​​​​​ER


-40°C ~ 10°C



-30°C ~ 30°C

Castrol EDGE Extended Performance

Pennzoil Ultra Platinum

Mobil 1 High Mileage



-30°C ~ 40°C

MOTUL X-cess

Now is easier to understand the SAE viscosity grade right? Need an example? Let’s say you live in a region with an average ambient temperature of 7°C (during Winter). 

What engine oil should you use?

Ideally, your synthetic engine oil should withstand that temperature. If you pay attention to the table above,  a 0W20 would be almost at the limit (10°C). That’s exactly the kind of situation you need to avoid. A better option in that scenario is a 5W30 synthetic engine oil. 

What Engine Oil Should You Use During summer time?

Let’s assume an average ambient temperature during summer of 28°C. The 5W30 engine oil would be in a similar situation as the 0W20 during winter. A slightly degraded oil may not maintain its properties when is closer to its operational limit. The solution would be to use a 5W40 during summer.

In fact, for this hypothetical example, a 5W40 would be the ideal engine oil for all seasons. Keep in mind that other considerations could be relevant as well. If your owner’s manual indicates a SAE 5W30 API SN Plus synthetic engine oil, you can then be sure that it can be used in temperatures exceeding 30°C, closer to the 35-38°C limit.

As you can see, besides SAE viscosity grade, there are other important engine oil specifications that you should be aware of. 

1. API Service Classification

The American Petroleum Institute (API) is in charge of certifying when an oil meets certain OEM quality and performance standards. Over time, the conditions to obtain the certification can change as the result of higher OEM quality requirements.

The latest API Oil certification (SN PLUS) was approved on November 9, 2017. The API SN Plus certification exceeds all prior classifications, in other words, any engine oil showing the API SN Plus certification can be used on older vehicles. The contrary is not true. If your owner’s manual recommends an API SN Plus engine oil you should not use a lower tier oil like API SJ or SM.

2. ACEA Classification

The Association des Constructeurs Europeens d’Automobiles (ACEA) is the European homolog of the American API service classification. The A/B class is used for passenger car motor oils accompanied by a number that represents the category. The higher the number the lower the oil viscosity and longer the service intervals.

3. Manufacturer Specific Certifications

In some cases, you may find supplementary certifications in the product description as GM dexos1 for example. In addition to industry standards, vehicle manufactures created its own engine oil specifications. That’s another reason for reading the owner’s manual and verify the precise engine oil required for your engine. 

Specific Engine Oil Applications – Other Factors To Consider

Now that you have a better understanding of engine oil properties and specifications it’s time to talk about particular engine oil applications. Current technology has allowed the creation of specialized oil types, suited for certain niche markets. We’ve already touched on them, but here’s a few in more detail: 

1. Extended Service Engine Oils: using premium formulas manufacturers were able to extend even more the service intervals like the Castrol EDGE Extended Performance with its 15,000 miles tag.

2. High-Performance Engine Oils: like MOTUL X-cess, offering ultimate performance to high power cars.

3. High Mileage Engine Oils: special additives and sealants make it possible to engine oils like Mobil 1 High Mileage to provide unsurpassed quality to engines with more than 75,000 miles.

4. Diesel Engine Oils: specialized heavy duty oils like Shell ROTELLA T6 provides the necessary protection to hard-working diesel engines.

5. Multipurpose Engine Oils: the wider category including products like our winner the Castrol GTX MAGNATEC suited for almost any engine in the market.

6. Severe Conditions Engine Oils: frequent stop-start, heavy traffic and other severe driving conditions were the inspiration for creating engine oils like the Pennzoil Ultra Platinum that includes unique compounds to help the engine during harsh conditions.

7. Cold Climate Engine Oils: ultra-low viscosity oils like the Valvoline SYNPOWER are intended to be used in regions where extreme cold demands a highly specialized lubricant.

Depending on your vehicle and type of driving, you can find a perfect fit for your needs. Remember, your choice should always comply with OEM recommendations. Both factors are important, your application and the appropriate viscosity/service level.