Best Oil for Portable Generator in 2021

Portable generators are not simple engines. The engine is the heart of the generator, and the oil is its blood.

How do you determine which oil to choose for your generator?

We’ll find out shortly.

The market is quite extensive, and there are different categories of oil. Perhaps you’re not sure of the difference between conventional oil and synthetic oil?

In this review article about the best oil for portable generator, we offer you a resource to learn from and compare different options.

5 Best Oil For Portable Generators 2021



Generac Full Synthetic Motor Oil 5W-30 SN

Generac Power Systems is at the forefront of generator technology. It’s a synthetic oil that’s gaining popularity among users of high-temperature motors in general, and particularly generators.

Traditional motor oil, which is refined from crude oil, changes over time and becomes thicker due to the effect of heat.

Of course, this naturally poses massive problems for lubricating engine oil. Thicker oil can’t move in the engine as intended and the engine stalls. If this has happened to you before, you’ll cherish the value of synthetic engine oil. This oil is fully synthetic and of great importance.


Honda 08207 10W30 Motor Oil

Best for heavy-duty construction machinery, Honda is another company known for its quality products with all mechanical parts. Their oil is no exception because it has been shown to make engines run quieter and longer, especially with Honda generators.

This oil is also classified as SJ by the API. This means that any 4-stroke engine manufactured after 1996 should be compatible with this oil.

The rating of the viscosity means that this oil is excellent for generators from equatorial to the temperate environment, but not as recommended for cold weather.

The price of synthetic oil always scare some people, but for the entrepreneur who relies on his generator every day or operates a portable welding machine, light towers, or other small motor-driven equipment.

It’s also a good choice for homeowners who choose oil for standby generators in warmer environments. This oil does a remarkable job of repelling paint deposits while maintaining viscosity throughout the year.



Cummins 3265336 Onan SAE 15W-40 Oil – 1 Quart

Cummins generators are highly respected all over the industry, and their Onan brand is one of the reasons for the reputation they enjoy. This gallon of engine oil has all you can expect from such industry leaders.

The oil has been tested in their factories to make their motor work as well as possible.

It’s designed for diesel engines but also works perfectly in gas-powered generators. It is formulated to resist viscosity caused by very hot engines, by increasing the efficiency of engines.


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

This Briggs and Stratton excellent synthetic is designed for use in small four-stroke engines like those found in some generators.

It overcomes the viscosity problem of conventional engine oils and is also a detergent oil that keeps the functioning parts of your engine trouble-free. This is essential for fuel efficiency and longer engine life.

Synthetic oil is also known to start working as soon as you light it. Again, as its molecular structure doesn’t need to be heated to lubricate properly, you can trust this oil during cold weather.


Castrol 03057 GTX MAGNATEC 5W-30 Full Synthetic Motor Oil, Green

In the first 20 minutes, 75% of engine wear occurs. This is the time it takes an engine oil to reach its optimal operating temperature. Unlike other engine oils that drain completely into the sump when the engine is switched off.

Castrol GTX MAGNATEC is a synthetic engine oil with smart molecules that adhere to critical engine parts and offers an additional protective layer. Immediate protection from the first moment.

This drastically reduces engine wear and makes critical engine components up to four times smoother.


Importance of Oil to a Generator

Before you begin your search for different oils and trying to figure out which oil is best for your generator, you first need to know how the oil affects your generator. Portable gasoline generators use engines that need oil to run properly.

These engines utilize the oil to lubricate their rotating assembly in the interior of the engine to ensure that the moving metal parts have a smooth, less resistant path.

This extends the life of your engine by reducing the engines wear for years to come. Over time and in many applications, this oil may begin to degrade and become less effective.

This can make your engine components more vulnerable to wear and tear. According to the manufacturer, adherence to the maintenance schedule for an engine oil change can largely prevent undesirable engine damage.

Related: Generator to run a furnace

How to Select the Perfect Oil for your Generator

When buying oil for your portable generator, there are a few important considerations to consider. To get a better idea of what type of oil you need exactly, follow these steps.

  • Read the Manual

Firstly, before buying oil for your portable generator, check the user’s guide supplied with the set. The manual part of such a guide on how to maintain the generator should mention the type of oil your generator engine requires exactly.

  • Determine the engine type

Different engine types require different oil types. Luckily, the vast majority of generators come with 4-stroke engines, which make the choice easier. There aren’t a lot of generators with 2-stroke engines.

The oil most commonly used in 4-stroke engines in generators, lawnmowers, and other related equipment is SAE 30. But you can also choose its synthetic variations, such as SAE 5W-30 and SAE 10W-30.

  • Check the Viscosity

Viscosity is precisely a property of the oil that determines how well the respective type of oil is suitable for cold weather. It represents the flow resistance of the fuel. You can find out the viscosity simply by looking at the name of the oil.

  • Hold on to reputable brands

Ensure you only purchase oil that has been produced by trustworthy companies. And the oil must have been approved by the Society of Automotive Engineers (SAE).

Some of the most prestigious names are Briggs & Stratton, Shell, and Generac. Check the list above to make sure you are buying quality oil with good ratings.

Related: What can a 4000 watt generator run

Frequently Asked Questions

Can I Utilize A Different Oil Brand From My Generator Engine?

When it comes to blending brands of oil with separate engine brands, there are a few things to keep in mind.

First, you need to check if your generator needs a certain oil brand or weight. If only the weight is given, you can most likely get along with any top-quality branded oil in the viscosity you need.

If your generator needs a certain oil, you have to make sure that you follow the manufacturer’s recommendations. If in doubt, call the generator manufacturer or contact their customer care for inquiries.

How Often Should I Change My Generator’s Oil?

Changing the oil of your generator is one of the important maintenance tasks you should do to ensure that your generator lasts for a long time. Refer to your generator manual to get the right maintenance schedule regarding the intervals for an oil change.

On average, you can decide to change the oil every 50 hours of use. Many generators have a runtime indicator, but for those who don’t, you’ll need to keep an eye on the number of hours you use.


Finally, thanks for reading thus far. We tried to include all the best oil that is ideal for your generator to keep working in tip top condition for a long time. The FAQs would also help you know how often you need to change the oil and what’s the most fitting oil for your generator brand. To recap, here are our top recommendations: