Best Oil for Portable Generator – Top 10 Options to Consider

Every portable generator owner wants the device to work smoothly and for an extended period. However, the machine won’t perform well if you use low-quality oil, or if the type of oil is not recommended for the model you have. Besides, using the wrong or low-quality oil may even damage the engine, and that’s probably something you want to avoid.

For example, portable generator oil with less lubrication ability may cause the engine parts to wear rapidly, and it will result in more maintenance costs. Also, you require oil with good viscosity for it to move to all the targeted parts of the engine properly.

It may be hard to determine what type of oil for a portable generator to purchase because of the numerous brands on the market. However, this review will make the work easier for you. I have analyzed the top options that allow a portable generator to perform excellently. Besides, I have evaluated the core features of each product, including its effectiveness, suitability for various machines, and their advantages and drawbacks.

Top 10 Best Oil for Portable Generators Reviews

There are numerous brands of oils available. They are priced differently, and they also deliver different results. Regardless of the machine, you are using, you should always pick the best oil, not only for the performance but for safeguarding the engine. Below are ten engine oil options that are excellent for portable generators.

1. Mobil 1 5W-30 – The Best Oil for Duromax Generator

Mobil 1 oil for generator, 5W-30

Mobil has its story of divisions and merges; formed when Standard Oil had to split in 1911, in 1999, it founded ExxonMobil with guess who. Its popular products, though, still retain familiar branding, including this oil. Mobil 1 is, by the way, the official oil of NASCAR. So you can be sure about its quality, but there are some details about its applicability that need to be cleared out.

A 5-quart bottle is the most convenient pack if you use your generator frequently. It belongs to the most generic 5W-30 class, protecting from high and (to some extent) low temperatures, and, as the manufacturer claims, it’s great for long runs if it’s changed rarely. Its composition was developed to prevent deposits and sludges that form on surfaces.

This one is synthetic, so it’s not recommended for starting generators; they need to work at least fifteen hours on some regular natural oil. After that, this oil delivers great results, especially if it does not get below -40°F. If you’re looking for the best oil for a small generator by Duromax or another vendor for the cold weather, this one is a great option.

2. Castrol 03084C Edge 5W-30 – The Best Oil for Portable Generators

oil for portable generator

Now being a British Petroleum company, Castrol was established in 1899 in London as the “Wakefield Oil Company.” Its Castrol oil, though, became a household name of its own, so the company renamed itself after it, and even after its acquisition by BP, it remains a standalone brand.

The name derives from castor oil which was added to WOC products early. Still, this one also has fluid titanium added, so it offers better protection under various speeds. It also helps your generator endure extreme temperatures, pressure, or vibration. These conditions are likelier to be suffered by portable generators, so if you take one with you to where there’s no power line, this oil by Castrol is a great choice.

The manufacturer boasts this oil surpasses its analog by Mobil 1 against viscosity breakdown. These tests might have been conducted under special conditions, but there is really nothing to complain about. As for this particular oil, it’s often named the best oil for inverter generator type.

3. Valvoline Daily Protection SAE 5W-30 – Extra Protective Oil for Duromax Generator

generator oil

The oldest manufacturer of automotive oils was established in 1866 by Dr. John Ellis, who developed the best motor oil formula of the time. No longer the biggest vendor, Valvoline still enjoys its premium reputation and retains it by making first-class products for the mass market.

Daily Protection SAE 5W-30 oil is the most versatile one that will keep your generator running at most temperatures, including tough conditions (though we wouldn’t recommend it if it’s indeed very cold outside). It contains additions that prevent deposits and sludges, which matters even more if you use your generator for long periods of time.

The highlight is that this oil is a conventional, non-synthetic one. And when it comes to conventional oils, Valvoline is the brand of choice, just like Mobil 1 with synthetic oils. You must pay attention, though, to purchase the type you need, as there are blends as well under this brand.

4. Pennzoil Platinum Full Synthetic – A Great Generator Oil for Long Winter Nights

Pennzoil 5w-30 oil for generator

Pennzoil is another American oil company established in 1913, the golden era for oil startups. Though Pennzoil is often considered cheaper and lower class than Valvoline, it all depends on the exact product. And this Platinum one is worth considering if your generator requires synthetic 5W-30.

Unique technologies by Pennzoil enable this oil to keep valves cleaner and protect moving parts from friction effects. It’s said to function well under extreme low or high temperatures (to just some extent, though). What’s most important for its usage in generators is that you won’t have to change it too often. If power often goes off in your area, or you venture away with a generator for long stays, this is a great option.

It also shows good results in winter – yes, in real cold winter. 5W-30 flows well in the cold, providing decent protection and ensuring your generator runs smoothly. You may find it the best oil for a Wen generator if you try.

5. Royal Purple 51130 10W-30 – The Best Oil for Westinghouse Generator

10w-30 oil for portable generator

A relatively new player on the market, Royal Purple was founded in 1986. Its synthetic oils, though, are very well-known and popular. This one is a synthetic oil, which increases fuel efficiency (important for generators as well) and goes better with ethanol-containing fuels.

Not as versatile as 5W-30, this oil is meant for warmer environments. But it does not only depend on the weather, as the temperature of the environment also depends on what you use it in.
If you read manuals for WGen6000, iGen2200, or other popular Westinghouse generators, you may discover that they require a 10W-30 oil rather than the standard 5W-30. That’s explained by the construction of the generator that keeps it warmer when working, so 10W-30 is a better choice.

So, it’s the best oil for a small generator by Westinghouse or another vendor that requires it. The main difference is, still, not between this particular oil and any other one, but rather between classes, and this one is what we recommend of all 10W-30 oils.

6. Amazonbasics Dexos1-Gen2 – Best Oil for Portable Generator


AmazonBasics is a branch of the renowned Amazon company that is dedicated to the delivery of basic home and office tools. Their range of products includes electronics, such as batteries, charging cables, as well as home gym equipment, video gaming accessories, and other items.

The AmazonBasics full synthetic motor oil Dexos1-Gen2 is purposed to protect your engine, even under severe weather conditions. You don’t have to worry about the climate of the area where you use the generator.

Though it is retailed and shipped by AmazonBasics, the oil is manufactured by Warren Oil. It is off-brand oil that can perform just as effectively as the best options out there. AmazonBasics acts as a retailer and guarantees the high quality of products it delivers to the customer. So, you can rest assured of the great performance of this oil.

While using this product, you are guaranteed longer drain intervals, in addition to a top-class blend of engine oils. This option is great for enhancing fuel economy, and it also provides remarkable protection from friction. As a result, you will find that you require less maintenance for your machine, thanks to using AmazonBasics oil, and your portable generator will serve you for a long.

More specifically, the oil has been formulated to limit low-speed pre-ignition. It has also been developed to surpass GM Dexos1-Gen2 requirements. The oil either meets or exceeds stipulations of SL, API, SN, in addition to SN PLUS. It also falls within the standards set by ISAC GF-5 & GF-4.

If you need high-quality oil for your portable generator for an affordable price, AmazonBasics Dexos1-Gen2 motor oil can be your best bet. It is my pick among the oils available, and I recommend this option to anyone.

  • Extended drain intervals
  • Dexos1-Gen2 compliant
  • Limits low-speed pre-ignition
  • Hard to figure out the remaining quantity of the oil in the bottle
  • Not certified by European vehicle manufacturers

7. Briggs and Stratton 30W – A Remarkable Option for 4-Cycle Engines


It is a firm that has garnered over 110 years of experience in engine oil production. Currently, the company is trusted by many users around the world for its superior quality products. What’s more, this brand has the backing of one of the largest service networks in the motor oil industry.

The firm is the biggest maker of small engines worldwide, as well as the best firm in pressure-washer marketing. What’s more, Briggs and Stratton is a top manufacturer of power generation machines and gardening turf and lawn care products.

The company’s innovations in motor oil production allowed for the constant improvement of products and increased customer satisfaction. Therefore, you can count on the quality of the products of this brand and purchase this oil for the great service of your portable generator. I want to highlight that the firm is dedicated to addressing the needs of its customers and strives to develop into an even more diversified enterprise.

All oil-based products of this firm have gained the approval of the leading engineers in the industry, and they are recommended in many operator instructions. This particular motor oil has been designed to comply with the hefty requirements of four-cycle engines fully. Moreover, it is a top-quality detergent engine oil that has been classified as SJ/CD through the API.

While using this product in your machinery, it is imperative to keep checking your engine regularly. Air-cooled engines burn at about one ounce of oil per cylinder each hour. While filling or refilling the oil, ensure that you only fill up to the dipstick mark. It is important to avoid overfilling.

I recommend you go through the engine oil types recommended for various engines to choose the perfect one for your machine. The reason is that various oil types work best at specific temperatures. Therefore, you should understand the ideal one to choose based on the temperatures you plan to use your portable generator at.

This SAE 30 variant is perfect for warmer temperatures and is most suitable for small to medium engines. Therefore, it is excellent for portable generators and such machines as lawnmowers.

  • Good viscosity
  • A good lubrication of the machine
  • Retailed in a comfortable-to-use bottle
  • Oil might sometimes leak off the bottle, despite the safety seal

8. Briggs and Stratton 2-Cycle Oil – The Best Oil with Fuel Stabilizer

Briggs and Stratton 2-Cycle Easy-Mix Motor Oil 16 Oz

Here is another great oil from Briggs and Stratton, and this option suits two-cycle engines. As I have mentioned, the brand has risen to become among the motor product companies trusted by many users across the globe. Being one of the most popular small engine producers, a top retailer of pressure washers, as well as a leading producer of pore geranium, garden, and lawn care solutions, you can never go wrong with this best generator oil.

This two-stroke engine oil has been created for enhancing the working temperatures of motor engines. I am ready to advocate that this motor oil has a better performance compared to a considerable amount of the generic engine oils available on the market today. It is because, for this oil, the brand utilizes an innovative semi-synthetic formula.

I want to note that the majority of engine brands can work with this two-cycle motor oil. Moreover, the product reduces the frequency of engine maintenance, thanks to its optimized formula. Also, it guards against cases of plug fouling.

Notably, this oil can perfectly blend with numerous fuel types. Moreover, it stabilizes fuel, thus, enhancing the longevity of your engine. You will surely note a heightening in the performance and stability of your machinery if you adopt the use of this oil for your portable engine.

  • Considerably inexpensive
  • Functions perfectly with numerous two-cycle outdoor engines
  • Allows a mix ratio of 50:1
  • Effectively prevents plug fouling
  • Not the most convenient design of the dispenser

9. Briggs and Stratton SAE 5W-30 – Suitable for Both Two-Cycle and Four-Cycle Engines

Briggs Stratton SAE 5W-30 Synthetic Small Engine Motor Oil 32 Oz

Here is one more remarkable engine oil from Briggs and Stratton. If you are seeking a multi-purpose engine oil that can be used both for two-cycle and four-cycle engines, this oil might be your best option. It is a top-notch detergent-based product that offers superb control over engine wear while maintaining and extending the equipment’s life. It performs remarkably under all outdoor temperatures.

The oil has been designed for use in small portable generators, as well as in the engines found in lawnmowers, pressure washers, tractors, and many other outdoor types of equipment. One major advantage of this synthetic oil is that it maintains its viscosity, even while in storage. It also retains clarity, even when used subsequently.

I want to mention that this product never ends up filled with sludge. Therefore, if your machine will be idle for a long duration, the oil will not lose its viscosity and lubrication capabilities. If you have several portable generators with different engines, it is worth going for this option that will fit them both.

Another advantage of this product is that the oil rapidly fires up engines just with one pull, even during hot summer and cold fall. It is ideal for generators, as this oil maintains its clarity for many hours. Although it comes at a high cost compared to other standard variants, this Briggs and Stratton oil minimizes the need to maintain your machine frequently.

  • Excellent for all types of two-cycle and four-cycle engines
  • Available in a convenient 32 oz. bottle
  • Retains its viscosity, even during storage
  • Prevents the rusting of engines
  • Relatively expensive

10. Generac 5W-30 – The Best Oil for Wide Temperature Range


Generac is an engineering factory established in 1959. It was the pioneer company to produce pocket-friendly home standby generators, together with the first engine created especially for the need of generator usage. Currently, the company is the top manufacturer of domestic backup generators.

This company produces the greatest range of power machinery within the marketplace. These products include residential, commercial, and industrial generators. The brand also ranks among the leading manufacturers and designers of fully automated and manual transfer switches, not forgetting the necessary backup accessories for redundant backup power equipment ranging to a maximum of 2MW.

Generac produces top-ranking combination units, powerful light towers, and trailer-mounted portable generators designed for different categories of the most cumbersome environments and industries. The company has also been a pacesetter in the home power washing industry and the engine oils from Generac and widely popular among homeowners globally.

This Generac 5W-30 product is a synthesized oil that quickly became popular among the owners of high-temperature motors and, particularly, generators. The thing is, conventional oils derived from crude oil usually change with time and also thin when exposed to high temperatures. Also, they become thicker under cold weather.

Moreover, if used as lubricating oil, there are a ton of problems that can arise. Thicker oils can’t move around the engine efficiently and, thus, may cause the engine to jam. But if you have never experienced this problem, then you have probably used high-quality synthetic engine oils only, and this option is one of such quality offers.

This oil is 100% synthetic and provides value for money. I want to note that it retains its chemical properties even under severe temperature changes. Thus, if you want to attain uninterrupted results when it is hailing, raining, or when it is hot outside, this oil will deliver that possibility to your portable generator.

Taking a closer look at the generic synthetic OEM oil, you will find that it prevents the formation and deposition of varnish and sludge deposits. The top-notch synthetic base that has been fortified with an efficient additive will ensure that you obtain a full shield against any breakdowns caused by viscosity.

Therefore, I would recommend this motor oil for all homeowners that use portable generators at different temperatures, from a hot summer day to cold wintertime. You won’t be disappointed with the performance this oil delivers.

  • Has been specially created for generators
  • Great for any temperatures
  • Protects against any deposits
  • Good viscosity
  • The pricing is considerably high compared to other oils in the same category

Buyers Guide ofor choose Generator Oil

If you want to treat your generator more consciously and rely on your knowledge more than on anyone’s recommendations (including ours), you need to know the basics. Here are the most important things you need to know about the oil in your generator and about other things you have to learn first.

How to Choose the Right Oil for a Generator?

The advice we give may sound too simple, but so are most problems. If you don’t feel sure, we don’t recommend going beyond the most basic troubleshooting.

Read the Manual

The simplest way to learn what type of oil you need for your generator is often to just read the manual. It may explicitly specify the oil you need (type, viscosity, season, and so on). Then you just need to purchase the one that fits the critical parameters.

Determine the Engine Type

It’s usually in the manual as well. The parameter you need is strokes: it matters whether your generator has a 4-stroke engine or a 2-stroke one (though chances are it’s 4-stroke nowadays).

Most 4-stroke engines are best served with SAE 5W-30 or SAE 10W-30 synthetic oils. If your model requires a conventional oil, you will probably be good with a SAE 30 one by any decent vendor.

Operating Temperature

When do you need your generator? It may be any season if you keep it just in case the power goes off after some disaster. But if you use it for some specific purpose, you must know the conditions it will be used under.

Winter tourism or work? Then you will need an oil designed for cold temperatures. The aforementioned 5W-30 is a good choice for 100°F and down to -20°F. If the expected temperature is below that, you better prefer synthetic oils to conventional ones. Just make sure the formula is specifically designed for extreme temperatures.

For hotter weather, you better opt for 10W-30 oils. They perform worse in the cold, getting thicker and less productive. In hotter environments, though, they can show much better results. You must also notice that some generators generate their own heat as they work and cannot isolate the engine from it, so 10W-30 will be a better choice for these models, even under conditions suggesting 5W-30.

Check the Viscosity

In general, viscosity is how smoothly oil pours at a specific temperature. The thicker the oil, the higher the viscosity. The higher the viscosity, the higher temperatures it requires to function properly. In winter, lower viscosity oils do the job, while those with high viscosity can just fail.

Should you always choose oils with lower viscosity? No. If you exploit your generator at high temperatures, thicker oils may perform better. The film that protects the moving parts is stronger when the viscosity is higher.

How do you know the viscosity of any given oil? Its viscosity at 100°C is defined by the number before the W in the name. For example, a 10W-30 oil has a higher viscosity than a 5W-30 one. That is why 10W performs better in the heat and 5W in the cold.

Stick to Reputable Brands

Reputation does not just appear out of the blue. It takes decades of selling quality products to form a good name. And if you look at the history of most brands selling motor oils now, you can track it down to 1911 (the year Standard Oil split after the Antitrust Act) and, for many, even earlier.

The price of a mistake is often too high when it comes to vital needs like power, especially after natural disasters or when touring extreme places. You can give an unknown brand a go when it comes to recreational use, or if you want to try it specifically and ready to deal with consequences like deposits and other harmful effects.

Synthetic vs Conventional Oil

Though the world is obsessed with everything natural, both conventional and synthetic oils have their pros and cons. And in most situations, synthetic oils perform better. They are suited to work under extreme cold or heat, they form fewer deposits, and they often contain additives that shape their properties the right way (extreme temperatures, better high-speed performance, and so on). In addition, their viscosity index is higher, which means more stability under changing temperatures. When conventional oils freeze and get too thick to circulate, synthetic ones remain functional. In addition, synthetic ones last longer, which is important if you run your generator for longer periods.

Conventional motor oil is made of refined crude oil, and though it may be considered more natural, its quality can vary. So do the particles it contains, so its effect is less predictable, and complications (like deposits and sludges) are more probable. On the other hand, conventional oils are at least half as expensive. They are also more fuel-saving. And with the right additives, conventional oils may perform better as synthetic ones may suffer from stratification in the cold.

For most generators, synthetic oils are a better choice unless specified otherwise. If you look at our top picks, synthetic oils prevail. Still, there are conventional ones that compete well.

What Type of Oil Is Required?

Again, that’s usually in the manual. If not, synthetic oils are a better choice; they may be more expensive, but you don’t have to change them as frequently. What else you should look at is additives: they can change the properties of the oil, so it can outperform the rivals under certain conditions.

What Does Oil Do for a Generator?

A gas generator has an engine with moving parts, which are set in motion by combustion. Its moving parts generate the power, but if they contact too much, they wear out too soon. If they get damaged, it can cause destructive effects, including explosions. To prevent it, oil is used to form a film between the metal parts. Due to this film, these parts run smoothly and safely. The oil, though, also wears out, so it needs to be changed regularly. Various engines and various conditions impact the demands on the oil you use; that’s why there are so many oils, and that’s why guidelines are necessary.


Though these questions may seem simple, the answers are never definite. We cannot answer how often you should change the oil without knowing which generator you have and how you use it. But we’ll tell you how to figure it out.

What is the best oil for a generator?

It depends on your generator and the way you use it. The answer may seem trivial, but it remains true.
Read the manual to see which types of oil are compatible with your generator. It depends on the engine type and some other parameters. The manufacturer is interested in showing the best side of its products, so you can recommend it to others. It means the vendor wants you satisfied.

As for conditions, you should select the oil by viscosity and other parameters concerning when and how you will use it. It includes the outdoor temperature, the length of the run, the intensity of usage, the weariness of the generator itself, and so on. Considering these parameters may motivate you to select a special type of oil with some additives that decrease fuel usage, prevent deposits better than others, or even generate thicker film than supposed to keep an old engine working.

How often should I change the oil in my generator?

It depends on your usage mode. Usually, experts recommend doing a full change after every 100 hours of use, but for portable and smaller generators, which you probably use, it may be 50 hours or less. It may depend, though, on conditions, your usage mode, and the type of oil you use.

If you don’t change the oil when necessary, it gets too hot and stops doing its job of decreasing the friction force within the engine. It’s good if your generator just detects it and stops. But it may result in wearing out as well, so you may have to repair the generator or even buy a new one.

When it comes to generators using splash systems (that is, most generators under 6000W), though, the reason you need to change oil is first of all its contamination, not heating and vaporizing. It’s recommended to change the oil every 36 hours of work. On pressurized systems, the interval may be longer, up to 60 hours.

What’s the difference between single-grade and multi-grade rating?

Multi-grade oils are better to use in cold weather. With these oils, you can start your generator easier without pre-heating. They are also good for quick start, and after the start, it reaches the surfaces faster, losing less time and preventing the engine from wearing out fast.

On the other hand, a multi-grade oil is more likely to leak out, so you need to be more careful with it. It takes experience to figure out when to use each type.

Can I use a different brand of oil for my generator?

Different from what? Usually, they recommend a certain type of oil that works best in your generator, and this type is sold by multiple brands. If you use, say, a regular 5W-30 oil, there won’t be any noticeable difference if you switch to one of this kind by another brand.

It may be different, though, if you opt for some oil with special additives. Different vendors can use different additives to improve the formula. If you expect some specific results (like increased fuel efficiency or better protection under certain conditions), you may get surprised even if you switch to another oil within the same class.

So, with generic oils, you can switch to a different brand with no bad consequences, but you can lose some benefits if you switch from a specific sort. If you still intend to, you better be prepared that your generator will use more fuel or require more frequent cleaning.

What could happen when I use too little or too much oil?

If you put too little oil into the generator, it may not suffice to cover all the contacting parts with the film. This may cause wearing out too soon, as parts of the engine start damaging each other.

But if you put too much oil there, neither will it cause any good effect. Too much oil will spread through the engine, ending up in the air cleaner base and the air filter. It can result in overheating and choking out. In the cylinders, extra oil can also produce smoke, with bad results as well.

You won’t have to worry and measure oil with a pipette, though. There should be more than an extra quart of oil to cause such consequences. You can find the optimal volume of oil for your generator in the manual. It’s better to add a little more than a little less.

Closing Remarks

I hope that this article helped you to learn more about high-quality engine oils one can use for their portable generators, and you have already picked the right option for your machine. Although the price is always a big factor while making purchasing decisions, it is not the only factor to evaluate when selecting a motor oil for your engine.

Therefore, make sure to compare different brands to see the money you can save if you choose a particular brand, as well as the performance you can expect to receive. Bear in mind that high prices don’t necessarily mean that the oil will work better than those priced reasonably, and in these reviews, you can find great fairly-priced options.

Also, consider the functionality of the selected engine oil. Some are designed for four-cycle engines, while others are made for two-stroke engines. Check if the brand is recommended for the type of engine of your machine. Note that some oils can be used with both types of engines.

Moreover, pay attention to the viscosity of the oil. Normally, oil thickens when it cools and thins when heated. The more resistance it has to thicken and thinning, the better. Resistance to thickening means that it will flow easily to the engine’s moving parts, while resistance to thinning implies that it will maintain a good film of lubrication.

Taking everything into account, I found the AmazonBasics Dexos1-Gen2 to be the best for portable generators. This oil is designed to safeguard your engine even under harsh weather conditions. Besides, it has extended drain intervals, and, therefore, you won’t have to change it frequently. This advantage of the AmazonBasics oil will, in turn, save you some money.

What do you normally look for when purchasing engine oil for your portable generator? Does the oil that you currently use always perform to your expectations? Leave a comment below and let me know about your experience.

You can use these oils for generators such as:
1. Portable diesel generator

Ronnie Collins

I’m Ronnie Collins. I’ve been passionate about gardening and woodworking all my life and even earned an MS degree in Botany from the University of Maryland. I’ve been working at a gardening company for a while, so I know the ropes about a whole lot of dedicated equipment such as the table saw, track saw, lawnmowers, chainsaws, garden hoses, and much more.

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