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Top 5 Best Generator Oil For 2022 – Reviews & Guide

Generators are an absolute necessity in today’s day and age as they run our appliances when the main supply goes out. However, just purchasing the best generator out there won’t do you any good. To maintain the optimum performance of your unit, you need to be careful about so many things. One of which is the choice of oil. Engine oils or motor oils are known to be essential for vehicle engines. But generator engines need them just as much.

Engine oils lubricate the internal components of the engine and keep the unit protected from wear. Modern engine oils contain extra additives to keep the engine clean as well so that your generator lasts longer. You may have learned about the exact specifications of the oil you need from the manual of your generator. But, we can guarantee that without the proper knowledge of these oils, your chances of finding the most suitable one out of the thousands of available options are very thin.

Don’t worry just yet, because we’re here with a list of the five best generator oils available in today’s market. From our experience with these exceptional products, you can make a good guess about how they’ll work for you. And yes, take a look at the buying guide we’ve attached at the end so that you don’t fall for the wrong ones.

 Best Oil For Generators- Top 5 Reviewed

01 AmazonBasics Full Synthetic Motor Oil – 5W-30 – 5 Quart (Editor’s Pick)

AmazonBasics Full Synthetic Motor Oil - 5W-30 - 5 Quart

Why It Stands Out to Us

We kept the AmazonBasics Full Synthetic Motor Oil at the top of our list because of several reasons. For starters, the lubrication is amazing. It keeps any generator’s engine components free from wear and other damages caused by friction. Besides, the viscosity grade we chose for today’s list makes the oil suitable for all seasons.

This synthetic oil keeps the temperature in check so that your generator doesn’t overheat and keeps running smoothly. AmazonBasics added a plethora of additives to this oil, which ensures protection from rust, corrosion, and sludge. It’s easy to say that this motor oil will increase the lifespan of your generator by years.

Another great fact about this oil is that it won’t cost you a premium price for the premium features it comes with. Overall, this well-thought engine oil from AmazonBasics is a top choice for any generator. If you’re in the market for the best generator oil, stop looking elsewhere and just make the purchase.

Our Experience With the AmazonBasics Full Synthetic Motor Oil

  • We received the oil with great packaging. It came in a very simplistic and stealthy-looking container. The cap was properly sealed and the bottle was very easy to hold and carry.
  • While we tested the oil in different generators, we collected samples at different stages to get insights into the quality it contains after a significant period of use. The lab reports from when we changed the oil indicated that the additives were still there and it could still run a generator for hours.
  • The lubrication was a class apart from most of the other engine oils we used. It kept the friction in check, which protected the internal engine components from wear.
  • We figured that the oil transferred heat throughout the generator engine to keep it cool for a longer period. The temperature management was more than satisfied with this oil.
  • Considering the viscosity grade, we tested the oil in different weather conditions and it didn’t let us down even a bit. Though we ran into some troubles in sub-zero temperatures, the overall performance in both hot and cold weather was superb.
  • It kept the engine factory clean and didn’t let sludge and other deposits build up in the engine. It goes without saying that a clean and well-lubricated generator will last longer than the rest. We can guarantee that the AmazonBasics Full Synthetic  Motor Oil has all the factors that can enhance the longevity of any generator.
  • Performance in RV generators was noteworthy. We tested this on different generators to power our motorhome appliances and we couldn’t find a single issue that would make us think twice about this oil.

What Could Be Improved

  • It seemed a bit thicker than other engine oils with the same configuration.
  • The material used in the container felt a bit cheap.

What Could Be Improved

  • The manufacturers could use better materials in the container.


  • Dimensions: 7.75x 4.25x 12.5 inches
  • Weight: 9.31lbs
  • Available Sizes: 3
  • Available Styles: 4
  • Available Configurations: 8


  • Superior protection against rust
  • Reduces friction
  • Exceptional lubrication
  • Great temperature management
  • Suitable for all weathers
  • Excellent viscosity resistance


  • Container material needs improvement

02 Castrol 03102 GTX High Mileage 5W-30 Motor Oil – 5 Quart (Runner Up)

Castrol 03102 GTX High Mileage 5W-30 Motor Oil - 5 Quart

Why It Stands Out to Us

The Castrol 03102 GTX Mileage is a performance beast. This synthetic blend engine oil is engineered to provide your generator engine superior wear protection, which eventually results in a great performance. The lubrication is so fine that generators start to feel more responsive as soon as you put this oil in them.

With a 5W-30 viscosity grade, this oil performs flawlessly in both hot and cold weather. It reduces friction and keeps the generator running at a stable temperature. In terms of cleanliness, there are very few oils that can compete with this one as it doesn’t let sludge or other deposits build in your unit.

Considering the features and functionalities of this oil, it’s safe to say that the Castrol 03102 GTX Mileage helps increase the longevity of any generator. If your generator is compatible with  5W-30 oils, we doubt you’ll find a better alternative to this one.

Our Experience With the Castrol 03102 GTX Mileage 5W-30

  • We loved the design and build quality of the container. Castrol didn’t cut corners in the packaging department, that’s for sure. The cap was nicely sealed and the placement of the handle was perfect for us to hold and pour oil from it.
  • For conducting our tests, we put this oil in different generators and took samples at various stages of the operation. We were very satisfied with the lab reports of those samples as the oil had plenty of life left in it even when we were on the verge of refueling.
  • The oil offered high-quality lubrication throughout the time. It reduced friction in the internal engine components, which also helped in keeping the temperature in check. Our generators ran smoothly even on full loads and the operational noise seemed to be reduced as well because of the lack of friction.
  • We tested the Castrol GTX Mileage in an RV generator and took the motorhome for a ride. It ran the generator for two days straight, powering all our appliances the whole time. We didn’t notice a single issue in the generator’s performance.
  • The oil seemed to keep the viscosity level intact in different weather conditions. We can confirm that the Castrol GTX Mileage can be trusted for all seasons.
  • In terms of cleanliness, this oil was an absolute champ. It covered the engine components with some kind of protective layer, which prevented harmful deposit build-up. We saw no sign of sludge during our time with the oil as well.
  • Our generators ran smoothly in different loads with the Castrol GTX Mileage. In some cases, we couldn’t tell if the units were running at a full load or ECO mode depending on the operational noise and temperature.

What We Didn’t Like

  • The performance wasn’t as good in sub-zero temperatures

What Could Be Improved

  • Castrol could have added some more additives to the oil

Our Suggestions

  • If you want to enhance the performance even further, go for the full-synthetic variant, which will cost you $2 extra.


  • Dimensions: 11.9x 9.8x 4.6 inches
  • Weight: 9.55lbs
  • Available Sizes: 5
  • Available Styles: 5
  • Available configurations: 2


  • Reliable brand
  • Exceptional cleanliness
  • Great burn protection
  • Decreased engine wear
  • Increased generator lifespan
  • Advanced additives


  • Not suitable for frigid climates

03 Castrol 03084C Edge 5W-30 Advanced Full Synthetic Motor Oil, 5 Quart

Castrol 03084C Edge 5W-30 Advanced Full Synthetic Motor Oil, 5 Quart

Why It Stands Out to Us

Coming from one of the leading names in the industry, the Castrol 03084C Edge is undoubtedly a great choice for generators. The best quality of this motor oil is its versatility to withstand different temperatures. Whether it is freezing weather or hot weather, this oil will keep your generator in perfect shape.

With exceptional temperature management and lubrication, this synthetic engine oil is easily the most recommended choice for people with RVs. While you’re in your motorhome enjoying your time on the road, the Castrol Edge will keep your generator running for days.

Not only does this oil protect your unit, but it also enhances the performance to the maximum. With the Castrol Edge in your generator, you won’t be able to tell if it’s running on full or half load depending on the noise and temperature. If you’re looking for engine oil for your RV generator, make no mistake and try out the Castrol 03084C Edge.

Our Experience With the Castrol 03084C Edge 5W-30

  • The packaging of this oil was exceptional. From the quality of the container to the sealing of the caps- everything was satisfactory. We loved the placement of the handle as the bottle was very easy to hold and carry.
  • We put this oil in several generators to test the performance and took samples of the oil at various stages of the operation. Even when it was time to change the oil, the lab results indicated that it had plenty of juice left.
  • With excellent lubrication, this oil kept the generators at their best. It reduced friction in the engine and kept the generators cooler compared to the other motor oils we tested.
  • We put this oil in an RV-ready generator and took it for a ride. The performance was very impressive and the operational noise seemed to have reduced significantly.
  • After testing it in different weather conditions, we can confirm that this oil performs great in both hot and cold weather. It also kept the generators running smoothly on different levels of pressure. We couldn’t tell if our units were on half or full load judging by the noise and temperature of the machine.
  • The cleanliness it offered was world-class. It kept the internal parts of the engine clean throughout the time. We didn’t notice any sludge buildup in the engine as well.
  • We noticed that the generator engine became more responsive as soon as we started using the Castrol Edge. We figured that the additives in the oil kept the engine components clean and lubricated so that they can be more adaptable to different commands.
  • Considering the quality of lubrication, temperature management, and cleanliness of this oil, it’s safe to say that this oil will keep your generator out of harm’s way for a long time. So, if you’re up for the enhanced longevity of your generator, you can give this a shot.

What We Didn’t Like

  • The life cycle of this oil wasn’t as long as we’d expected
  • The price fluctuates a lot

What Could Be Improved

  • The life cycle could be prolonged a little


  • Dimensions: 4.3x 8.3x 12.9 inches
  • Weight: 9.29lbs
  • Available Sizes: 6
  • Available Configurations: 4
  • Certifications: API


  • Attractive container
  • Great performance
  • Prevents the formation of sludge
  • Exceptional resistance to extreme pressure
  • Protection against viscosity degradation
  • Perfect for RV generators


  • Lifespan not satisfactory

04 Valvoline Advanced Full Synthetic SAE 5W-30 Motor Oil 5 QT


Why It Stands Out to Us

Valvoline is a renowned name in the engine oil industry and the Valvoline Advanced is one of their top-selling product lines. The Valvoline Advanced SAE 5W-30 comes loaded with features and functionalities that you won’t find in other oils.

For starters, it offers extraordinary wear protection that enhances the longevity of your generator by a great margin. The lubrication is so great that you’ll notice a change in the operational noise of your unit. This full synthetic motor oil is suitable for both low and high temperatures, so you can count on it throughout the year.

Despite having all the supreme features, this amazing engine oil doesn’t cost as much as its competitors. If you’re looking to boost the performance of your portable generator, go for the Valvoline Advanced 5W-30 without any hesitation.

Our Experience With the Valvoline Advanced Full Synthetic SAE 5W-30

  • Valvoline did an amazing job in terms of the packaging of this oil. The container arrived in perfect condition and the cap was properly sealed as well. We found the design very user-friendly as the bottle was very easy to hold and pour oil from.
  • We tested the oil in a few generators and the performance was satisfactory in all of them. We took samples at various stages of the operation and found nothing to complain about from the lab reports. The additives were present even when it was almost time for a refuel.
  • In terms of lubrication, we were very pleased with the Valvoline Advanced 5W-30. It seemed to add a protective layer on the engine’s moving parts, making them immune to the friction and keeping them out of harm’s way.
  • The reduced friction allowed the generators to run smoother and as a result, the operational noise lowered significantly. Though putting this oil didn’t instantly make our generators quiet, it definitely made them run without any inconveniences.
  • We tested this oil in different weather conditions and the results were flawless. Having a 5W-30 viscosity grade allowed it to work great in both hot and cold temperatures.
  • The cleanliness of this full synthetic oil was noteworthy. During our time with the oil, we found no trace of sludge and the engine seemed factory clean throughout the time.
  • Valvoline put superior additives in the oil, which helped keep the engine in perfect condition. We can confirm that using this oil will definitely increase the longevity of any generator.

What We Didn’t Like

  • Not suitable for sub-zero temperatures
  • The price fluctuates a lot

What Could Be Improved

  • Better materials could be used to make the container

Our Recommendations

  • Make sure to shake the container before pouring oil from it. This will mix the additives nicely with the oil and you’ll get the best performance out of it.


  • Dimensions: 8.22x 4.6x 12.6 inches
  • Weight: 9.5lbs
  • Available Sizes: 6
  • Available Configurations: 6
  • Certifications: API


  • Reduces engine wear
  • Great cleanliness
  • Suitable for different weather conditions
  • Prevents degradation
  • Versatile operation
  • Well-designed container


  • Not suitable for sub-zero temperatures

05 Valvoline High Mileage with MaxLife Technology SAE 5W-30 Synthetic Blend Motor Oil 5 QT

Valvoline High Mileage with MaxLife Technology SAE 5W-30 Synthetic Blend Motor Oil 5 QT

Why It Stands Out to Us

If your generator features a 4 stroke engine, you’ll be looking for something that provides superior lubrication and cleanliness. Considering the requirements of a typical 4 stroke engine, there are very few oils on the market that can compete with the Valvoline High Mileage SAE 5W-30.

This synthetic blend motor oil is engineered to enhance the longevity of your generator. Its viscosity grade makes it suitable for both hot and cold temperatures. With exceptional lubrication, it prevents friction in the internal components of the generator engine, making the generator run smoother than ever.

Another great fact about this oil is that it retails at a very affordable price range compared to the other products of its quality. So, it won’t fall too heavy on your wallet as well. Overall, it’s a great option that you can pick for your generator any day of the week.

Why It Stands Out to Us

  • This oil came with perfect packaging and the sealing of the container seemed satisfactory as well. The handle was nicely placed as we could pour oil directly from the bottle.
  • Considering the viscosity grade and additives, the oil seemed like the perfect choice for four-stroke generators. Four-stroke engines usually generate a lot of power, requiring superior lubrication and heat management facilities. The Valvoline High Mileage SAE 5W-30 seemed to tick all the boxes there.
  • While testing in different generators, we took samples of the oil halfway through our use and at the time of refueling. We were surprised by the quality of the oil after several hours of heavy use. At the time of refueling, we expected the oil to burn out completely but the lab results claimed that there were plenty of additives still left in the sample.
  • In terms of cleanliness, we didn’t find any issues. The oil kept the generator engine’s internal component factory clean and sludge-free until it was time to refuel. It’s a rule of thumb that a clean generator engine will perform more flawlessly and so it did.
  • Friction minimization was another noteworthy feature of this motor oil. We noticed that the operational noise of the generator sounded a lot smoother with this oil, which means the lubrication was fantastic. We also found no wear and tear in the moving components of the engine.
  • Performance was exceptional in both low and high temperatures. However, if you happen to live in areas with higher temperatures, there are other variants like the 10W-30, or 10W-40 that you can use.

What We Didn’t Like

  • The oil only prevented intermediate or mild breakdowns.

What Could Be Improved

  • The container could be made of better quality materials


  • Dimensions: 8.22x 4.6x 12.66 inches
  • Weight: 9.449lbs
  • Available Size: 5
  • Available Configurations: 6
  • Certifications: API


  • Great packaging
  • Exceptional protection against degradation
  • Efficient and thorough cleaning
  • Reduces the likelihood of leaks
  • Suitable for all seasons
  • Prolongs generator lifespan
  • Easily affordable


  • Not suitable for sub-zero temperatures

Best Portable Generator Oil: Buyer’s Guide

Best Oils For Generators

1. Read the User Manual Carefully

The instruction manual of any accessories is one of the most important aspects to be considered. The instruction manual allows you to obtain a complete operation of the machinery. A generator needs some knowledge to operate correctly throughout its entire lifespan.

However, not all manufacturers provide a helpful instruction manual. Considering this aspect allows a novice user to obtain an operation according to his expectations. Even an instruction manual can avoid generating some errors or wrong functions.

2. Types of Oil

a) Traditional

Traditional oil is also best known for being the oil that incorporates almost no external attachments. When it comes to a new machine or generator, there is no need for an oil that contains additives. It is also the most economical oil available today.

b) Synthetic Blend

This is an intermediate option between traditional oil and some of the characteristics and additives of fully synthetic oil. It can be suitable for improving the lifespan of a generator without spending a large budget for that.

c) Full Synthetic

When it comes to synthetic oil, they’re tailor-made with top-shelf additives. It requires a higher budget, but it is the most efficient option to enhance the lifespan of any machinery. You also can get more mileage out of it, if you’re using it in vehicles. In generators, full-synthetic oils ensure smooth performance and longevity.

3. Oil Properties

The different properties of the oil can allow it to obtain a more complete and adequate bear for the best care of any machinery. Viscosity or density are two of the most important aspects to consider. Each can be adapted from a type of climate in a kind of machinery.

There are also other unique properties such as solubility, flash point, and pour moment. Each of these aspects is usually specific to a particular generator. The different generators on the market must also be considered here.

4. Generator Type

a) Natural Gas Generator

This is one of the most popular generators that require natural gas to operate. This type of generator can produce high power output and a high noise level when driving. New machines usually require high-quality oil to maintain good performance.

b) Portable Generator

Portable generators usually generate a moderate level of power. However, they are easy to transport and use in different locations. These generators tend to run on gasoline most of the time. The functionalities are intermediate, but it is not as heavy an option as the natural gas generator.

c) Electric Generator

The electric generator is one of the newest options. In general, it is a much lighter generator than the previous options and produces a low noise level. A battery pack is used to store energy. Despite these features, it is a generator that also requires high-quality oil.

5. Oil Viscosity

The viscosity of the oil is an aspect that must be considered according to the climate. Density is related to the operation of the oil in cold temperatures. When it comes to cold weather, thinner oils with a low viscosity are suitable. These oils can be poured easily and quickly.

When it comes to oil with a high viscosity, it is a thicker option. Using this oil will be more complex and slower to pour the liquid at cold temperatures. Thus, lubricant thickness should be considered with the typical climate of a home or city in mind.

6. Operating Temperature

Generator oil, like any machinery oil, has an operating temperature range. This temperature range indicates the appropriate temperatures at which oil can function correctly. Consider this vital aspect to avoid damage to the generator machinery.

Generally, the oil temperature should be kept between 230 and 260 degrees. An oil that is not designed for cold climates could freeze and damage the mechanics of the generator. Oil designed for cold temperatures may be too liquid in a hot environment.

7. Quality

In most cases, we can find different oils with different functionalities. An excellent way to find out which oil is the best quality is to look at the type of oil. In general, fully synthetic oils are usually of high quality.

8. Price

It is possible to find inexpensive motor oil starting from $50. There are also more expensive, high-quality oils that’ll set you back $400.


1. What will happen if you add too much or too little oil to your generator?

Ans. Adding too much oil to a generator or any machine can cause oil leakage. Oil can allow the engine to choke when transferring to the air filter, air cleaner box, or any other component.

2. Can you use synthetic diesel oil in your gasoline engine?

Ans. The specifications and viscosity requirements of the engine must be taken into consideration. Considering this, you can use diesel engine oil for a gasoline engine.

3. Can you use a different brand of oil than your generator’s engine?

Ans. It is not recommended to mix different generator oils of different brands. Each brand has its formula that should not be combined with other oils.

4. How much oil can your generator consume?

Ans. Within a 24-hour operating period, you will consume ½ or ¾ of a quart.

About the author

Jamie Masterson

With decade-long experience as a generator technician, Jamie has worked with USA’s top generator manufacturers and suppliers as an independent contractor.

The long years of service to the industry has taught Jamie the ins and outs of troubleshooting, repairing, and maintaining all kinds of generators in home, industrial and outdoor settings.

Jamie thinks this platform is a great opportunity to share his tips and tricks with you so you can make the most of such power equipment for better living.

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