Best Oils for Generators of 2023 – (Top 4 Picks & Reviews)

Should you choose the SAE 10W-30, SAE 5W-30, or the SAE 10W-40 engine oil for your generator? Not even sure what these numbers mean? Learn all about the best generator oils here!

My generator comes with a manual that lists the recommended type of oil used every time the generator needs a refill or an oil replacement. Understandably, the right oil increases the generator’s performance and protects the risk of costly damage to the generator. But then, in my search for the ideal generator oil, I noticed a surge in the number of new generator oil brands.

This challenge set me on a mission to find some great varieties of generator oils. After months of research, I created a round-up list with some of the best oils for generators, especially if you’re looking for alternatives to the big brand names.

So, if you have been struggling to find and choose the best oils for your generator, this detailed buying guide will be precisely what you need to optimize your generator’s performance.

The Best Oils for Generators – Comparison Table

Generator Engine OilViscosityOil TypeCheck Price
SAE 10W-30

Check Price
Shell Rotella T4 Triple Protection Conventional 15W-40 Diesel Engine Oil
SAE 15W-40

Check Price
Triax Power 4-Cycle SAE 30W Full Synthetic Small Engine Oil,
SAE 30-30W

Check Price
Ultra1Plus™ SAE 10W-30 Conventional Motor Oil
SAE 10W-30

Check Price

The Best Oils for Generators – Products Review

HONDA MOTOR OIL 10W30 QT – Best Overall Generator Engine Oil

This motor oil is one of the best for 4-stroke or 4-cycle generator engines. This Honda engine oil is also top-recommended in the SAE 10W-30 categories.

Key Features

  • Motor oil for a 4-stroke generator
  • SAE10W-30
  • API-SN
  • Non-synthetic

This motor oil by Honda is at the top of our list because it is a well-known product offered by a well-known motor oil brand and lubricates rather quickly. It also meets and exceeds the SN-API standards.

As an SN oil type classified in the motor oil classifications by the American Petroleum Institute, this Honda Motor oil is among the finest quality engine oils available today. It represents a unique motor oil blend made of sheer-stable polymer additives and the best quality base stocks. Although these make the engine oil costly, the blend does the best to protect your investment. How? Honda’s engineering for this oil allows it to resist thermal breakdown and viscosity changes. It has an impressively high flashpoint of 200 degrees Celsius.

This will be a good choice if you want high-quality generator oil to enhance your engine function and efficiency. Thanks to its efficiency, oil usage is low, so this oil saves you money.

What I Liked

  • SAE 10W-30
  • High-efficiency rate and low oil usage overall
  • Good value for money
  • Unmatched quality oil for a 4-stroke engine generator
  • Unique, high-performance oil blend
  • High flashpoint
  • Ideal for small engine generators, lawnmowers, and even pressure washers

What I Didn’t Like

  • Expensive

Verdict – This is the best overall engine oil for your generator, ensuring optimal function when starting and running. It might be pricey, but it offers excellent value for money.


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Shell Rotella T4 Triple Protection Conventional 15W-40 Diesel Engine Oil – Best Heavy-Duty Equipment Generator Oil

Next on this list is the Rotella engine oil by Shell. It is a high-performance, high-quality 4-stroke synthetic engine oil blend that will enhance the health and the performance of your generator’s diesel engine.

Key Features

  • SAE 15W-40
  • Synthetic oil blend
  • API CK-4

If you are looking for engine oil for your heavy-duty building generator, you need the most powerful oil blends designed for heavy-duty usage, and this engine oil by diesel will get the job done quickly.

This oil powers the engines of heavy machinery and some of the biggest generators thanks to the T4 technology. This intuitive technology is proprietary to Shell. It is an additive (additive technology) that ensures the ultimate protection of diesel engines, especially for real workhorses. It offers 50% more protection to the engine than other oils. Its efficiency is impressive – it reduces lubricant-related (DPF) blockage rate. In turn, minimized DPF blockages maintain the efficiency of the oil while also controlling the exhaust gas emissions; hence the cleanest engine units between oil drain intervals.

The advanced additives in this oil also protect oil oxidation, enhancing the oil’s and engine’s efficiency. The oil boasts a higher level of shear stability, greater control over the oil’s viscosity, and optimum pressure for the engine oil.

What I Liked

  • This oil is ideal for larger generators that power buildings and other big machinery.
  • SAE 15W40 protects the engine from wear or deposits
  • Minimal oil breakdown
  • Ensures the cleanliness of the engine and prevents DPF blockages
  • Excellent shear stability hence a higher level of viscosity control
  • Best-rated engine oil for diesel engines

What I Didn’t Like

  • Not reasonable for use with small generators

Verdict – For anyone who relies on their generator for powering their homes or offices in the long run rather than for emergencies, you need an engine oil that enhances the engine’s performance, and this is it!


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Triax Power 4-Cycle SAE 30W 100% Synthetic Generator Oil – Best Generator Oil for Small Power Equipment

For the best performance of your generator or even a garden tractor, this SAE 30 engine oil would be ideal.

Key Features

  • For use in a 4-Stroke engine
  • 100% synthetic engine oil
  • 4x drain interval increase
  • A high percentage of zinc in the formulation protects the engine from wear

This Triax engine oil will be an ideal fit if you are looking for a fully synthetic engine oil for your 4-stroke generator. The oil formulation boasts excellent anti-wear properties thanks to its zinc formulation. It also leads to a quiet engine, little to no smoke, and excellent performance, especially when the generator needs to work extra hard.

What I liked

  • Versatile SAE 30 30W Engine oil
  • A high degree of thermal resistance
  • It prevents smoking, oxidation, and sludge and keeps the engine clean
  • You can use it at very low temperatures.
  • All-season engine oil – remains viscous at lows of -45 degrees Fahrenheit.
  • It contains built-in stabilizers and friction modifiers

What I Didn’t Like

  • This is a lesser-known brand, and most people may shy away from it

Verdict – Get this engine oil if you live in icy areas and want to ensure that your generator starts and runs efficiently and consistently.


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Ultra1Plus™ SAE 10W-30 Conventional Motor Oil – Best for Older Generators

If you have a powerful 2000W+ gas-powered inverter generator that you have been using for months, this conventional motor oil could be a good option for you – it’s not recommended for new engines.

Key Features

  • SAE 10W-30 motor oil
  • API SL
  • Gasoline oil blend formulated with premium additives and Paraffinic base stocks belonging to Group II.

We recommend getting this oil blend for the engine for a generator that has been running for some time and has several hours under the belt. It is a simple but effective gasoline motor oil blend boasting great anti-wear, anti-foaming, antioxidant, dispersant, and detergent properties. This formulation exceeds the API SL performance requirements.

What I Liked

  • Rated for use in generators as it meets and exceeds the API SL requirements for performance
  • SAE 10W-30
  • Reduces fuel and lubricant consumption
  • Longer cycles between oil changes
  • Reduces deposit formation
  • It prevents engine wear, which is good if your generator is a workhorse.
  • Affordable

What I Didn’t Like

  • Avoid it if you have a new generator. Get a synthetic oil instead
  • It’s not a popular brand

Verdict – This is an affordable engine oil when you have an older generator whose parts are used for the job, and you’re not afraid of the oil damaging the engine.


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Buying oils for generators – What to look out for

Start with the basics listed in the User’s Guide or Manual.

Generators always come with a user guide. Even if you are looking for oil for your first-ever generator, the user guide gives a breakdown of everything you need to know about your generator, how to care for it, what oil to use, problems to look out for, and other safety recommendations. Details of the ideal oil for the generator are also included in the manual. So, start your search for the correct oil here.

Oil features or specifications

The viscosity of the oil

Before you buy any oil for your generator, check its viscosity. You will find this information either on the manual or online in suggestion boards and forums, as shared by other users or owners of generators similar to yours. The SAE 10W-30 is the most recommended oil for the generator.

But what exactly is SAE 10W-30?

Well, SAE represents the grading system for the generator oil, an oil viscosity grading system created by the Society of Automotive Engineers (SAE). It represents the viscosity of the engine oil, rated at 10W in a cold engine and then at 30W once the engine heats up.

Note that the SAE 10W-30 grade differs from the SAE 5W-30 – the latter represents a much thinner engine or generator oil measured at 5W when the motor is cold.

As per this grading system for the oil’s viscosity, grading ranges from 0W, representing the thinnest oil for the generators, while the highest rating of 60W represents the thickest oil. Here, W represents winter (not watts or weight) and connotes the oil’s viscosity levels when the engine is cold (at different degrees). The second number, 30, is a value that signifies the efficiency of pumping the oil when it is heated at 212 degrees Fahrenheit (100 degrees Celsius) or higher.

But why is the viscosity of engine oil important? If you are looking for motor oil for your first generator, you need to know that the oil’s viscosity will affect the oil’s consumption and the ease at which your generator starts and runs in case of extremes in temperature. So, high-viscosity oil is thicker at warmer temperatures, meaning that you will use less oil in the generator, and the rate of wear and tear is relatively low with such a generator. The SAW 10W-30 is an excellent example of this oil, which is why it is highly recommended.

That said, beware that the thinner, less viscous generator oils allow for a faster start-up for the generator and an overall reduction in fuel use.

Choosing the appropriate oil viscosity for your generator is essential because the wrong engine oil (viscosity) would lead to occasional contact between the motor components. If this problem is unchecked, the generator will start acting up, and you will have to deal with expensive damage, repairs, and replacements.

So, think of the SAE number as an indicator of the oil quality. And avoid using the wrong oil to protect engine parts from premature wear.

Operating temperature

As mentioned above, this is important in ensuring the generator’s optimal function and protecting the parts from wear. Experts note that the SAE 5W-30 oil is the ideal generator oil type if you live in icy areas – this engine oil will only start at such low temperatures. Beware, however, that the consumption of this oil increases at high operating temperatures, and you should always check the oil level before running the generator.

Engine Types – 4-Stroke or 2-Stroke

By now, you know that most generators have a 4-stroke engine rather than the 2-stroke engine. This is a significant difference to take note of. With the 4-stroke engine generators, the oil and fuel are utilized differently. But with the 2-stroke engines, you could buy the pre-mixed solution or even mix the fuel and oil at home as per the recommended ratios. So, it would be best if you thought of this before buying the generator oil.

Oil brands for generators

First, you should buy engine oil from a reputable brand. Second, avoid the super-cheap generator engine oils – cheap will always be expensive, and if there is one thing whose quality you should never risk, it is the quality of the engine oil that you buy for your generator. Third, there are many options online, and you will always find a good quality generator oil priced reasonably.

Final Verdict

Generator oils have different properties and are designed for 2-stroke or 4-stroke engines. The recommended oils above are ideal for 4-stroke generator engines. They are highly rated by SAE, have high shear stability, protect the engine from wear, and prevent emissions. If you are looking to buy any of these oils, make sure that the oil you get will enhance the performance of your generator, depending on its usage and overall performance in the long run.


What is the meaning of an API SL-rated engine oil?

This is the term that the experts use to describe a series of engine oils that boast a high level of shear stability and high-quality performance, and also for multi-graded engine oils that can be used in different power equipment and vehicles.

What is the role of zinc in engine oil formulations?

ZDDP or zinc dialkyl dithiophosphate is often found in engine oil formulations because it creates a layer of protection on the engine’s metal surfaces, allowing the engine to withstand stress on the engine components like the camshaft.

What’s the difference between synthetic and conventional engine oils?

Synthetic or synthetic oils use high-quality base oils (less-refined oils), common with conventional engine oils, so they are more stable than conventional oils. Conventional oils are less stable chemically, they oxidize quickly, and because they break down easily, they lose their protective properties quickly.

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