How Much Oil Does a Portable Generator Take?

Have you gone through your generator’s manual after purchasing it? Studying your generator manual is crucial as it would give all the information you need for safe operation. This will help you know how much oil your generator takes to keep it working efficiently.

Generally, portable generators hold 400 to 700 milliliters of oil. As you might expect, smaller inverter generators typically use less oil than larger models. Nearly every portable generator requires a different amount of oil, so check your generator’s user manual to find out the exact amount.

The following are the detailed explanations for your portable generator’s total oil consumption.

How Much Oil Does a Portable Generator Use?

The amount of oil a generator can take depends on the brand and the size. Most portable generators take oil between 400 to 700 millimeters, but some take much less or much more.

Always remember to check your oil regularly. If you forget to check your oil level, you may be surprised when your generator begins to size up a few days after use. 

Do not worry if you are very forgetful and may find checking your generator oil level challenging. Modern generators have low oil shut down features that prevent substantial damage if the oil goes very low.  

Hence, if your generator stops working, first check the oil level. Above everything, make it a golden rule always to change your oil after every 100 hours. To avoid accidents, always make sure you have given the generator time to cool down before making the change. 

Examples of How Much Oil Portable Generators Use

As said earlier, the amount of oil a portable generator can take depends on its size and brand. Below are some generators from various brands and the amount of oil they can hold. 

Westinghouse Generators

Generator ModelHow Much Oil It Can Hold
iGen2200350 ml
iGen2500350 ml
iGen4500600 ml
WGen2000600 ml
WGen3600600 ml
WGen3600v600 ml

The Westinghouse generator manual emphasizes the importance of not overfilling the generator. According to the manual, overfilling the generator can lead to severe engine damage and damage to the surrounding property. There is usually a marker to indicate the recommended fill level, so ensure you aren’t over or underfilling your unit with oil.

Briggs and Stratton Generators

Generator ModelHow Much Oil It Can Hold
P2200 PowerSmart500 ml
P2400 PowerSmart500 ml
32000A Portable500 ml
1200A SPRINT Portable500 ml

Firman Generators

Generator ModelHow Much Oil It Can Hold
P03602600 ml
ECO 4000620 ml
ECO 4000RE620 ml

Like the Westinghouse generator model, Firman generators emphasize the importance of ensuring you fill your generator to the indicated level (without overfilling). According to the Westinghouse generator manual, ensuring that a generator is on a flat surface before filling enhances the accuracy.  

Champion Generators

Generator ModelHow Much Oil It Can Hold
170cc Inverter560 ml
224cc Inverter 5560 ml
2000 Watt Inverter470 ml
3500 Watt Inverter560 ml

Though this information helps identify the amount of oil your portable can hold, it is essential to read through the manual. This will help realize the specific oil capacity of your generator and help prevent the dangers of the oil overfilling or running low. 

From this information, it is clear that the amount of oil a portable generator can take is not the same, even for generators made by the same company. That is why it is highly recommendable to check your generator manual. 

This will give you the exact information you need about your generator operations. You will also know the dos and don’ts of your generator. Therefore, make it a habit of going through your manual immediately when you purchase it.

Why Do Portable Generators Need Oil?

The oil acts as a lubricator in the moving parts inside the generator hence reducing friction on the moving parts to prevent them from wearing out prematurely. Oil also protects the generator against corrosion and keeps dirt away from critical areas like bearings. 

Using high-quality oil helps keep air and moisture from the generator’s engine. As a result, your generator is not at risk of overheating or potentially breaking down. If you use the generator regularly, it is crucial to change the oil after every 100 hours of use. This will help in extending the generator life.

What Oils Are Suitable For a Portable Generator? 

No one oil fits all generators. Some oils are suitable for some generators, while others are destructive. Choosing appropriate oil for your generator is crucial in maintaining and repairing any internal combustion engine. Besides, using inappropriate oil can cause damage or destroy the engine. 

You will find a wide range of portable generators on the market that caters to various needs. Thus while shopping for your generator’s oil, there is more to look at – not only the quantity and the type of the oil. For example, synthetic and conventional oils are two different oils that serve different needs and are good for different generators. 

Most portable generator engines use diesel, gasoline, or natural gas. Each of these has distinct characteristics that will affect how you treat your machine when adding oil. There are also specific recommendations based on the model of the engine. For example, if you have a Honda engine generator, you need to get Honda oil. 

Best Oil for Portable Generators

There are many different oil brands and types to choose from, and it can quickly get very confusing. Below are a few of the best oils for portable generators to hopefully make your decision just a little bit easier.

1. Generac Full Synthetic Motor Oil 5W-30 SN

Generac power systems are at the forefront of generator technology. It is a fully synthetic oil gaining popularity among users of high-temperature motors in general, specifically generators.  

Generac full synthetic oil is conventional motor oil refined from crude oil and changes over time and becomes thicker due to heat. As a result, this poses a severe problem for lubricating engine oil. Conventional motor oil is viscous and cannot flow in the engine as expected. This results in the stalling of the engine. 

If your generator engine has ever stalled before, you understand the importance of using synthetic engine oil. Generac Full Synthetic Motor Oil 5W-30 SN is fully synthetic and of great importance to your engine, especially if the engine heats massively. 

2. Honda 08207 10W30 Motor Oil

Honda 08207 10W30 Motor Oil is best for heavy-duty construction machinery, for example, Honda engines. Honda is known for its quality products with all mechanical parts, and its engine oil is no exception. The engine often runs quieter and longer, especially with Honda generators. 

Honda 08207 10W30 Motor Oil is grouped as an SJ by the American Petroleum Institute. This implies that any four-stroke engine manufactured after 1996 should be compatible with the oil. 

Regarding the Honda 08207 10W30 Motor Oil viscosity, the oil is best for a portable generator in the equatorial environment. 

The oil is not recommended for cold weather as it can become thicker, with cold weather denying it its lubricating function. Though the price of this portable generator is very high, it’s the most valued oil for people who rely on their generators for daily operations or operate portable welding machines, light towers, or any other small motor-driven equipment.

If you are a homeowner and need oil for standby generators and are in warmer environments, then Honda 08207 10W30 Motor Oil should be your choice. This type of oil does a recommendable job in repelling paint deposits while at the same time maintaining viscosity throughout the year. 

3. Cummins 3265336 Onan SAE 15W-40 Oil

The oil is fully synthetic motor oil designed for diesel engines and works well in gas-powered generators. It has a formula meant to protect against viscosity caused by very hot engines by increasing the efficiency of engines. 

Given that the Onan brand makes the oil, you can bet on the quality of the oil based on the Cummins portable generators made by the same industry. 

4. Briggs & Stratton SAE 5W-30 Synthetic Motor Oil

This oil is fully synthetic and designed for small-stroke engines like generators. Unlike traditional motor engine oils, the generator oil overcomes the viscosity problem. Besides, it is detergent oil that keeps the functioning parts of the portable generator trouble-free. It is essential for fuel efficiency and longer engine life.

Briggs & Stratton SAE 5W-30 Synthetic Motor Oil is known to start working immediately. Also, its molecular structure doesn’t need to be heated to lubricate properly. Hence it can work perfectly during cold weather. 

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

It is one of the best oils for portable generators with smart molecules and works perfectly on critical engine parts, and offers an additional protective layer. In some generators, 75% of the engine wear occurs in the first 20 minutes.  

This implies the period it takes for engine oil to reach its optimal operating temperature. Castrol GTX MAGNATEC offers immediate protection when the generator wears out 75% in the first 20 minutes. Hence it drastically reduces engine wear making critical engine components up to four times smoother.

How to Select the Best Oil for Your Portable Generator 

There are various things to consider when purchasing suitable oil for your portable generator.

Carefully Check the User’s Manual 

Though we have stipulated above the best oil which can work well and not damage your portable generator engine, it is essential to read through the manual given by the generator manufacturers before buying the oil. The manual would give you specific guidelines on maintaining the generator and the exact type of oil the engine requires. 

Determine the Type of Engine 

No one type of oil fits all generators. However, most common generators come with four-stroke engines making the decision easier. 

Identify the Viscosity 

Precisely, viscosity is a property of an oil that determines how perfectly the respective type of oil is fit for cold weather. In other words, viscosity represents the flow of resistance of fuel. You can often find this information on the container with the oil. 

Investigate the Oil Brand 

Only purchase generator oil from reputable brands. If you purchase your oil from prestigious brands such as Briggs and Stratton, Shell, and Generac, you are assured of getting high-quality oil for your portable generator. 

You can also look at the reviews and ratings left by previous buyers on a specific oil. This will help in making decisions on the type of oil to purchase. 

How Much Oil Does a 5000-Watt Generator Need?

The 5000-watt generator has an oil capacity level of 5.7-gallon tank of gasoline. This type of generator is very convenient and versatile. Besides, the generator would offer you plenty of power for your needs when outages occur.

5000-watt generators have a recoil start and cold start technique to ensure a faster start when freezing. The design improves safety using a push to reset the circuit breaker and enable low oil to shut off the sensor. 

This includes an oil funnel for an easy change. The generator has 1.2 quarts of recommended 10W-30 engine oil. 

How Much Oil Does a 2000-Watt Generator Need?

A 2000 watt generator has an oil capacity of 42 quarts. An example of a 2000 watt generator is the Honda 2000 generator. According to its manual, it needs to have 10w to 30 weight conventional mineral engine oil. It is advisable to use synthetic oil on this type of generator.

Though synthetic oil is four times more expensive than traditional motor oil, they are very crucial for a smooth operation of a generator. Synthetic oils can lubricate an engine’s working parts faster than conventional motor oils. They are the type of oils to go for when in cold weather or running your portable generator during cold winter months. 

How to Maintain a Portable Generator’s Oil

It is crucial to have a standby generator if there is a power outage. However, buying a portable generator is not enough as you have to maintain it in good condition and use it when need be. So how can you maintain your portable generator for unexpected power outages?

1. Keep You Portable Generator Clean When Not in Use

When you keep your generator sitting in a room for many days without using it can get pretty dirty. Dust can build up or even debris and molds. As a result, it can destroy critical components which negatively affect its functioning.

Though it is difficult to keep wiping your portable generator, especially when not using it, you can purchase a generator cover. The cover will protect your generator from dust and water if it is waterproof. 

Suppose you cover your generator when not in use. Always remember to remove the cover before starting the generator. This is because it can act as an insulator hence causing overheating.

If you cannot buy a generator cover, do not worry. Your generator will still be okay if you wipe it at least once a month. 

2. Always Empty the Portable Generator’s Tank After Use

After your generator has performed your intended duties, you need to empty it into a gas container. Leaving oil in the fuel is detrimental and may cause the formation of gum deposits. Gum deposits build up can hinder the performance of the generator.

Though it is recommendable to have enough oil for your portable generator, it is not right to leave it in the fuel tank.

3. Get Some Back-Up Fuel and Filters

Power outages can take hours or even days. Hence it is recommendable to have enough oil on hand to last out an average power outage. Having backup oil filters is also very advisable as they will help you if they need replacement.

4. Take Note of the Portable Generator’s Wattage Capacity

Go through your generator’s manual to make it can handle the voltage you plan on using on your generator. All generators do not share the same specifications, and hence you will need to check the exact manual for your generator. 


How much oil a portable generator takes depends on the model and size of the generator. It is best to use synthetic oils as compared to conventional oils for most generator models. This is because synthetic oils have specifics that protect your generator.

I hope this information was useful so next time you go shopping for portable generator oil, you better understand what you’re looking for and your options.


Hubert Miles

I've been conducting home inspections since 2002. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and an FHA 203k Consultant. I started to help people better understand whole-house and portable generators.

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