Best Synthetic Motor Oil Reviews with Buying Guide (Oct. 2018 )

If you are looking for engine oil in this day and age, make sure it is a synthetic oil. They generally last longer and are an overall better choice for engines. 

Here, we have reviewed the best synthetic oils of 2018 to help you choose the perfect motor oil for your vehicle. 

Note: Make sure to check the user manual before purchasing any engine oil. The engine oil requirement of the motor should match the specification of the engine oil you buy.

Our Top Recommendation 

The Mobil 1 120874 Synthetic Motor Oil is our pick of the range when it comes to selecting the engine oil. It has various benefits including a longer engine life, a smoother engine and also better engine performance all round.

It uses an advanced patented formula that prevents wear and tear of the various engine components, delivers oxidation and thermal stability, and also returns better gas mileage. It ensures excellent lubrication on all the moving parts.

The Mobil 1 oil has been our go-to choice for years and is still our No.1 recommendation.

1. Mobil 1 120764 Best 5W-30 Synthetic Oil

Best Synthetic Oil

If you don’t want to risk damaging your engine and want it to run for years without any issue, the Mobil 1 120863 is the way to go. It is one of the top-rated full synthetic oil which generally last for around 7000 miles or so before requiring an oil change. However, check your user manual to know when you should change your engine oil.

This engine oil is manufactured in the US and meets the American Petroleum Institute standard. It is priced on the higher side but you can have a piece of mind with this engine oil.

The oil is rated for 5W-30 and can work well in a wide range of climate conditions. The oil is also quite thin which helps the quick flow of the oil in all the major oil components. It makes sure all the engine components are well lubricated.


  • Works just as advertised
  • Lasts a very long time
  • Lubricates the engine components really well
  • Quick flow of oil in all major components


  • Pricy in comparison to others. 

2. Valvoline SynPower 0W-20 Full Synthetic Motor Oil

If you are looking to buy an engine oil which will not only protect the engine but also improve your gas mileage, the Valvoline SynPower 0W-20 is worth trying out.

While we don’t recommend buying engine oil just because it claims to return more mileage, we think this one is an all-around good product. The oil does the cleaning work really well and also smoothen the engine during idling.

It is priced lower than the competition and you won’t experience quality differences between this oil and its competition.


  • Helps maintain high fuel efficiency
  • Excellent after-sales support
  • Priced competitively


  • Poor Jug design makes pouring oil difficult

3. Pennzoil 550046122 Platinum 5 quart 5W-20 Full Synthetic Motor

We loved the Pennzoil 550046122 Full Synthetic Oil for its highly competitive price and excellent oil properties. But we found out that the price of the oil changes quite a bit. Make sure to price check before making your purchase.

The oil is tailored to keep your engine components clean. It features a superior active cleansing agent which cleans out engine sludge better than synthetic blend oils and conventional oils.

If you use a quality oil filter, you can expect to run on this oil 7500 miles or so before requiring an oil change. It is Dexos and API certified and should work on most of the automobile manufactured in 2004 or later.  


  • Lubricates engine parts faster than the competition
  • Leaves less deposit on the back of the valves


  • The price changes frequently for no reason

4. Shell Rotella T6 Full Synthetic Heavy Duty Engine Oil 5W-40

Heavy Duty Engine Oil

Shell engine oils need no introduction. They have been in the market for the longest time and they offer varieties of engine oils. The Shell Rotella T6 is a full synthetic oil designed with trucks in mind. But it works just as well on small diesel powered vehicles too.

The engine oil is specifically designed to work well on heavy-duty trucks. As such, the oil has got one of the best lubricating property. Using this oil, you can expect your vehicle to be free from wear and tear for a long time. We also found the engine to run a bit smoother with the usage of this oil.

One thing that is worth noting is that the bottle that the oil comes in is kind of brittle. There are multiple reports of oil leaking with even with smallest of drops. So, if you are planning to keep in in the boot of your vehicle, make sure to keep it protected.


  • Lasts generally longer
  • Cheaper in comparison. 
  • Works great on all kinds of automobiles ranging from trucks to motorcycles


  • The oil container has a tendency to crack and break

5. Royal Purple 51520 5W-20 High Performance 

If you have come across Royal Purple oil for the first time, here’s a fun fact: the oil from this manufacturer is purple in color! We are pretty sure that none of the other brands have purple color oil to offer.

Royal Purple is one of the premium brands which makes both full and synthetic blend motor oils. To associate yourself with this premium brand, you will, however, need to shell out a bit more money.

The added cost may be very much worth it if you live in a region that isn’t too cold. We found out this oil doesn’t work too well in cold climates. We heard a prominent clatter for the first few seconds after we cranked up the car during a cold startup. The clatter wasn’t previously audible.

On the bright side, with this synthetic oil, we achieved higher gas mileage. And at normal temperatures, the engine sounded smooth and a bit quieter.


  • Improved fuel efficiency
  • Runs engine smoother and quieter
  • Excellent wear protection


  • Expensive
  • Oil is purple in color which makes determining oil burn difficult
  • Doesn’t handle cold starts well

6. Mobil 1 High Mileage 5W-30 Motor Oil

This Mobil 1 High Mileage is a fully synthetic engine oil that is designed for vehicles with high mileage. It’s one of the best-selling high mileage motor oil on Amazon and it’s rated really well too.

It’s a 5W-30 engine oil which is designed to work on both hot and cold climates. It lubricates all the engine parts really well and helps reduce sludge and other deposits. We found that this synthetic oil also lasts quite a while longer when compared to other high mileage car oils.

While this oil may not offer anything ground-breaking, it works exceptionally well as a reliable engine oil.


  • Best choice for automobiles with high mileage
  • Help reduce sludge and deposits
  • Works well on all weather conditions


  • None

7. Liqui Moly 2041 Premium 5W-40 Synthetic Motor Oil – 5 Liter Jug

Best Engine oil

The Liqui Moly 2014 is a fully synthetic motor oil and it has one of the best performance of any engine oil. It also works well in varying weather conditions. It has got very high lubrication reliability at both high and low temperatures.

The oil is made in Germany and promises outstanding engine cleanliness. In addition to that, after using this oil in our test car, we found the engine idled a lot smoother and the engine clatter was also well controlled.

You can get this engine oil in different size bottles ranging from 1 liter all the way up to 5 liters. The price is also good considering the fact that it is imported all the way from Germany.


  • Priced well
  • Better engine performance and less engine clatter
  • Engine idles smoother with this engine oil
  • The bottle comes with a pull-out spout which eliminates the need for a funnel


  • Doesn’t work very well on heavy diesel trucks

8. Valvoline High Mileage 5W-30 Synthetic Blend 

The Valvoline High Mileage Synthetic Blend is designed for automobiles with high mileage on the odometer. It’s a good choice especially if your car has run 75,000 miles or more.

One thing you will need to keep in mind is the fact that it is a synthetic blend oil and not a full synthetic motor oil. So, if you have full synthetic oil on your car, it’s best to look at the alternatives. It’s generally not a good idea to mix full synthetic oil and synthetic blend oil unless it’s an emergency.

The oil extends the life of your engine by using components such as anti-oxidants and extra detergents. It will keep the old engines cleaner by removing sludge and deposits. It also prevents oil breakdown preventing engine-clogging sludge.

Lastly, you should know about the pricing of this oil. For whatever reason, the price of this oil keeps changing. So, if you find the price to be a little too high, it’s a good idea to check back a few days later.


    • Protects the engine on higher mileage vehicles
    • Slightly re-seals leaks in engine components
    • Works well on large trucks
    • Engine idles smoother


  • Price fluctuates too much

9. MAG1 61790-pk6 Full Synthetic 5W-30 SM Motor Oil

MAG1 51790-pk6 offers value for money like no other motor oil on this list. But it’s cheap doesn’t mean it’s not of high-quality. In fact, it’s one of the best-rated oils at Amazon. It works well on all kinds of gasoline engines. We found that the engine runs a lot smoother with this oil and there’s less noise too.

The design of this bottle is worth mentioning too. It’s clear and you know exactly how much oil you have poured and how much is left. It also provides protection from engine wear during cold start-ups.

However, if you were looking for synthetic oil for a diesel motor, you will have to look elsewhere. This oil is specifically made for gasoline engines and we don’t recommend using it for any other type of engines.


  • Works well on turbo-charged engines
  • Great price per quart
  • Clear bottle design makes reading the amount of oil poured easily to gauge
  • Dexos1 certified


  • None

Is Synthetic Oil Better for your Car?

Types of Synthetic Motor Oils

Today, synthetic oil has almost completely replaced conventional oil. It’s no surprise especially given the fact that they last longer, lubricate better and work well in varying climates.

They are made from compounds that are made artificially by breaking down and rebuilding petroleum molecules. They are tailored to provide optimal lubrication properties.

There are two types of synthetic oils that you should know about.

Synthetic Blend Oil

The synthetic blend oil, as the name suggests, is a mix of conventional motor oil with synthetic base stocks. Since it uses synthetic base stock in the conventional motor oil, you will get more protection and added performance. It is when you compare it to the use of conventional oil.

However, when you compare it to the full synthetic oil, it lacks behind in terms of performance and doesn’t last as long. On the bright side, you can usually get it at a lower price.

Full Synthetic Motor Oil

Just like the synthetic blend oil, It uses a synthetic base stock. But instead of using conventional oil, it uses different sets of additives that boost the performance of the oil. They are made from complex refining processes and have higher quality and purity. They are tailored to meet the demands of newer turbo-charged engines.

However, you will need to keep in mind that not all full synthetic oils are created equal. Different manufacturers use different additives in their oil resulting in varying performance and protection level.

They are usually more expensive than conventional oil and synthetic blend oil. But the extra price is easily justifiable and if you are using an automobile that is made later than 2012, we recommend nothing but full synthetic oil.

Buying Guide to Find the Best Synthetic Oil 

The market is flooded with different engine oils and all of them seem to claim to be the best oil for your car. Here are the things you should consider before making your purchase.

1. Read the User Manual

Doesn’t matter how good or premium an engine oil is, if it doesn’t match the specification of your car engine, it’s a no buy.

You can check the manual of your vehicle to see what oil the manufacturer recommends. Many a time, you will find them specify brands who make the best oil for the car. It will also mention the type of oil that is put in the car during the delivery.

The manual further includes details like the recommended oil weight and the oil replacement interval.

2. Make sure to use the right type of oil

Almost all modern cars use synthetic oil today. If your car was manufactured in 2012 or earlier, there are high chances that it uses synthetic oil. Some of the cheaper naturally aspirated cars, however, may still use conventional oil. You can find details regarding the oil that your car uses in the user manual.

There are two types of engine oils you will find today: Full synthetic engine oil and Synthetic Blend Oil. Just make sure that you don’t mix different types of oil together.

3. Use of the right kind of Oil Filter

We find that people do a lot of research and almost always get the right kind of oil for their engine. But when it comes to changing the oil filter, people will either not change it on time or even worse get a Chinese knockoff which doesn’t do the filtration all that well.

It’s best to use an OEM supplied oil filter as they generally work the best with your engine. Even if you can’t find it nearby you, make sure the specification of the OEM and the 3rd party oil filter manufacturer is the same.

4. Check for Certification

At any cost, avoid any engine oil which isn’t branded and doesn’t come with any kind of certification. If you live in the US, make sure the oil you buy has the American Petroleum Institute’s star logo.

All engine oils sold in the US are tested by the API. Only the brands that meet the standard can place the institute’s logo on the package. You will also find SAE (Society of Automotive Engineers) viscosity number on the label. In addition to that, it also tells if the oil has passed the Energy Conserving Test.

FAQ on Synthetic Oils

Q1. Who makes the Best Motor Oil?

Ans: Mobil 1, Valvoline, Shell, and Castrol all make great Synthetic Motor Oil. Be sure to check out how long the oil lasts before making your purchase. You can’t go wrong with any of the aforementioned brands.

Q2. Is it okay to switch brands of Synthetic Oil?

Ans: It is okay to switch brands as long as the specifications between the oils are the same.

If you really need to (in case of an emergency), you can go as far as topping up an engine loaded with 5W-30 a 5W-40 oil and you will still have no problem. Minor viscosity differences are acceptable. Just make sure that the API under the engine oil specification matches that of the engine oil.

Q3. Which oil is thicker 5w30 or 10w30?

Ans: ‘5w30’ and ‘10w30’ are the viscosity grades which tells how the engine oil performs within the range of average and cold temperatures.

The first number in the viscosity grade represents the low temperature (i.e. 5 or 10), ‘w’ stands for winter and the second number represents the high-temperature rating.

Between the 5w30 and the 10w30, the 10w30 will be thicker during the cold climate. While choosing between the two, you will need to keep the climate you live in into consideration. For places that reach as low as -30°C, it’s a safer bet to choose the 5w30 engine oil.

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