How Much Oil does a Generator Take? (Portable & RV)

generator oil capacity

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An oil change is an integral part of generator maintenance. Changing your generator’s engine oil regularly will help it perform better and last longer.

However, you just can’t pour a whole bottle of motor oil into the crankcase. The bottle may have too much or too little oil, which is both bad for the generator.

Thus, knowing the oil quantity of your generator is essential.

So, how much oil does a generator take?

The quantity of oil in a generator varies depending on the brand, type, and size of the generator. Most camping generators take anywhere between 350-1300 milliliters of oil. Whereas, onboard RV generator models take about 1-2 quarts of oil depending on the size.

In this post, we’ll take a look at the oil capacity of the most common RV generator brands and sizes. We’ll also answer various other questions related to generator oil capacity.

Note: Always refer to the user manual to find the exact quantity of oil your specific generator model needs to use.

How Much Oil does a Generator Take?

Motor oil is a lubricant that helps lubricate the engine and its moving parts. This reduces wear and tear by reducing the friction between the internal moving parts of the engine.

The oil capacity of a generator varies depending on the size of the engine. The bigger the engine, the more oil it will take and vice versa.

Usually, camping generators will take about 350-1300 ml of oil, depending on the size. On the other hand, a Cummins Onan generator will take about 1-2 quarts of oil, depending on the size.

Here is a table with the oil capacity of some of the most common brands and sizes of generators used in RVs.

Cummins Onan Generator

Generator ModelOil Quantity
QG 2800I1 quart/946 ml
QG 40001.6 quarts/1514 ml
QG 5500 EFI2 quarts/1892 ml

Honda Generator

Generator ModelOil Quantity
EU2200i0.46 quarts/440 ml
EU3000iS0.58 quarts/548 ml
EU7000iS1.16 quarts/1097 ml

Yamaha Generator

Generator ModelOil Quantity
EF2000iS & EF2200iS0.42 quarts/397 ml
EU3000iS1.37 quarts/1296 ml
EF6300iSDE1.37 quarts/1296 ml

Westinghouse Generator

Generator ModelOil Quantity
iGen2200 & iGen25000.37 quarts/350 ml
iGen45000.63 quarts/596 ml

Champion Generator

Generator ModelOil Quantity
2000-Watt Inverter0.5 quarts/473 ml
3500-Watt Dual Fuel0.6 quarts/567 ml
4500-Watt Inverter0.5 quarts/473 ml

Briggs and Stratton Generator

Generator ModelOil Quantity
P24000.42 quarts/400 ml
P45000.6 quarts/567 ml
Q65001.05 quarts/1000 ml

Firman Generator

Generator ModelOil Quantity
2100-Watt Inverter0.4 quarts/380 ml
3650-Watt Inverter0.63 quarts/600 ml
4200-Watt Inverter0.6 quarts/567 ml

Generac Generator

Generator ModelOil Quantity
GP2200I0.36 quarts/340 ml
3650-Watt Inverter0.6 quarts/567 ml

The oil capacity of the generator mentioned is accurate for the models above. However, you need to check the user manual of the specific model if your model is not listed above.

The first generator brand (Onan) is an onboard RV generator. All the other brands and models mentioned are portable inverter generators.

What Factors Determine the Quantity of Oil a Generator Needs?

When it comes to generator oil capacity, it depends on various factors. Here are the two most common factors that determine how much oil a generator takes.

The Size of the Engine

The engine size is the #1 factor in determining the oil capacity of a generator. In general, the larger the engine, the more oil it needs and vice versa.

For example, a 300 cc engine is big and will need more oil compared to a small 125 cc engine.

Moreover, the oil capacity of similar size engines on different brands may also differ. This is because every brand uses different technology to design the engine and thus the differences.

Therefore, it is important to check the user manual of your specific unit to determine the quantity of oil before changing generator oil.

Changing Oil Filter

Changing a dirty oil filter during an oil change is important as the dirt and grime from the filter will contaminate the new oil. Moreover, replacing your old oil filter with a new one will determine the quantity of oil necessary during an oil change.

For example, a Honda EU2200i takes about 0.46 quarts/440 ml oil. However, because the oil filter also has some oil in it, you need to add the extra oil to fill up the new filter you just replaced.

Though the amount of extra oil you need to add depends on the size of the air filter, it will not vary by a big margin.

Where can I Find the Oil Capacity of my Generator?

There are thousands of camping generators out in the market today with different oil capacities. This makes listing all the models in this post not only difficult but impractical.

However, there are easy ways to find out the oil capacity of your specific brand of generator.

Refer to the Users Manual

The user manual of your generator has everything you need to know about your generator, including the oil capacity. It will tell you everything about the type of oil to use, the frequency of change, and how much oil your specific unit takes.

However, if you have bought a used generator or lost the manual, then there are other ways to tackle this problem.

Look Online

One of the easiest ways to find specific things related to your generator is to look into the manufacturer’s website. Head on to the manufacturer’s website and look up your generator model and download the user manual.

If you want you can even print it. However, if your model is old and discontinued by the manufacturer, then you need to perform a google search with your specific model.

Call A Pro

If you have tried both the methods above and failed, it’s time to call a professional. Call up the local dealers and mechanics in your area, and they should be able to help you out.

You can also visit your manufacturer’s servicing center and talk to a mechanic or a technical person to get the information.

How do I Check the Oil Level in my Generator?

Checking your generator’s oil level regularly keeps you up to date with the amount of oil in the engine. It also warns you about any potential issue before it becomes catastrophic.

Though generator oil checks should be done every day before starting the unit, they can also be performed whenever necessary. 

Turn off the generator and let the engine cool down, as checking the oil on a hot engine can be dangerous. Moreover, turning off the engine and letting it cool down lets the oil settle down, giving you an accurate level.

Once the unit cools down, place it on a hard-level surface. In the case of an onboard RV generator, park the RV on a level surface to get an accurate oil level reading.

Now, locate the yellow oil fill cap/dipstick on the engine of the generator. Unscrew the dipstick completely, wipe off the oil on it and screw the dipstick back into the engine completely.

Unscrew the oil fill cap again and now you will get an accurate level of the motor oil inside the engine. Add oil if below the recommended fill level or drain oil if above the recommended level.

What Happens if your Generator Oil Level is Low?

Running your generator with low engine oil is bad news. Motor oil is essential to the primary function of an internal combustion engine.

It helps to lubricate the internal parts to reduce friction. This helps the generator perform at its peak and ensures long working life.

However, as the oil level goes down due to a leak or oil consumption, the friction inside the engine increases. This increases the wear and tear of the internal components until the engine seizes completely.

Generally, most modern camping generators come with a low oil shutdown system that helps prevent damage to the engine. However, the most common signs of low oil are burning oil smell, strange sounds, overheating, and reduced performance.

To avoid catastrophe, check your generator’s oil level regularly and top up as it comes down below the recommended level. It is a good practice to check the oil level before the first start of the day.

What Happens if your Generator Oil Level is High?

Overfilling a generator with oil will also hurt the generator. With too much oil in the crankcase, the oil starts to foam as the crankshaft and the piston move.

This is especially true when the generator is running at a higher RPM. The constant whipping of the oil inside the crankcase heats the oil, breaking it down quickly.

A broken-down motor oil loses its ability to lubricate the internal parts of the engine, resulting in premature engine damage. Moreover, the excess oil from the engine will be forced into the air filter chamber, causing the generator to choke and stall.

Identifying if you have overfilled a generator is pretty easy. Generally, an engine with high-level oil will leak oil, smoke from the exhaust, the spark plug will fault, and produce loud engine noise.

From accidentally adding more oil to fuel entering the crankcase, there are many reasons why oil may increase suddenly. However, the solution is to drain the excess oil and check the oil level regularly.


Changing the oil in your generator is an important step in making sure your generator performs well and lasts long. But many people don’t know the correct amount of oil their generators take making them ask how much oil does a generator take.

It depends on the type, brand, and size of the engine of your generator. Most camping-style generators take about 350-1300 ml of oil and RV generators take 1-2 quarts.