How to Break in a Generator [8 Easy Steps]

It is like breaking in a new pair of new shoes. A portable generator should go through a series of steps (pun intended) to break it in for use. There are a few easy steps to take to protect the engine from damage and ensure a long life.

As we have stated in related articles, how long your generator will last will depend on how you care for it. Breaking in your new generator can extend its life well beyond the warranty period, and most well-maintained generators will last 10-15 years. Although it takes a bit of time, the precautionary steps are detailed here and done by a novice generator owner and those seasoned operators.

Steps for Breaking In Your New Generator

1. Carefully read the operator’s manual. The manual (physical or online) should recommend your generator’s type and amount of oil. While most manuals do not include specific breaking-in steps, they recommend changing the oil within the first few hours of operation.

[Note] Filling the generator with oil and initially running at load does not ensure the oil has lubricated all the necessary engine parts.

2. Supplies Needed to Lubricate the Generator. Following the guidelines in the operator’s manual, you will need:

  1. Fuel – most generators will use gasoline, diesel, propane, or dual uses of gas or propane. Use a clean authorized fuel can.
  2. Oil – What kind of oil does a generator use? Most manufacturers will recommend a 10W-30 weight oil for average climate temperatures
  3. Funnel – this makes pouring the oil into the reservoir easier. [Do not use it for both the fuel and oil, as residual gas can contaminate the lubricant).

3. Lubricate the Spark Plug Chamber. A diagram of the engine should be in the operator’s manual, and it will show the location of the spark plug.

  1. Carefully unscrew the spark plug and remove it. Add a few drops of oil conditioner into the chamber.
  2. Slowly pull the recoil starter 8-10 times to allow the oil to lubricate throughout the chamber. [You are not attempting to start the generator at this point, only slowly lubricating the section.)
  3. Replace the spark plug securely.

4. Add Oil and Fuel to Respective Reservoirs—the amount of oil the engine will take is listed in the operator’s manual. 

  1. Fill the reservoir to the recommended level using the funnel. Only add the recommended level and do not overfill. 
  2. As the oil flows into all the intended areas, wait a few moments before checking the oil dipstick (on most generators), then top off to the required amount.
  3. Fill the fuel tank from a clean authorized fuel can. Avoid using an old receptacle with dirt or debris that could contaminate the engine.

5. Start the Generator. Read the directions for starting the generator, as the steps are not the same for recoil starters and electric start buttons.

However, in most cases, you will find a switch that allows you to set the engine to an “on” or “off” position. This setting may also include a “choke” option, or it may be a separate switch depending on the model of the generator.

A recoil starter may require several pulls, and patience is needed. Each time you pull the recoil, the lubrication process flows further into the chambers.

Once the generator has started, you may need to address the choke option, so follow the operator’s manual instructions.

6. Run the Generator. Follow the manufacturer’s guidelines for the minimum time the generator should run initially. If there is no recommendation, allow the generator to run for a full hour without adding any load. 

After one hour, turn the generator off, drain the remaining oil from the tank, and then refill it. Draining the oil allows any residual metal debris collected to run out.

7. Optional Second Start. This step is optional. Allowing the engine to run for another non-load hour will ensure that all metal bits collect in the oil. You will again drain the oil and refill before running the engine and drawing a load.

8. Do a Load Run. The final step to breaking in your generator is to operate it with a load. You will plug in sources that draw between 500 and 1000 watts of power during this step. Then, with a load drawing power, allow the generator to run for one to two hours, and the time should sufficiently break in your generator for full power use.

There are varying opinions on this step, however. Some information states the new generator should run at 75% of its wattage output, while others indicate the run should last until the fuel runs out. Either way, do not break in the generator at peak load. 

How to Break in a Generator

The Purpose of Precautionary Steps in a Generator

Most new generators arrive from the factory without oil. Attempting to start one, called a dry start, can damage the engine’s cylinder walls with minute residual metal pieces from the manufacturer and new metal debris caused by the piston moving inside the cylinder.

The process of creating a cylinder leaves a pattern of small ridges (cross-hatch) that the piston can grind against if no lubrication is there. Proper lubrication with oil fills the cross-hatches so the piston can move up and down without friction.

A piston must settle into its optimal operating position. If no oil is in the cylinder to protect it, the piston will grind against the cylinder walls, creating metal debris and allowing carbon build-up. Carbon build-up over time causes fumes to leak through places where seals are not tight.

Performing Regular Maintenance Checks

The life expectancy of your generator will depend on your regular maintenance checks and seasonal storage. 

Follow the recommendations in your operator’s manual for changing the oil and filters. Remember to do regular visual checks of the engine components to ensure no loose screws or bolts, rust from water, and check the exhaust for signs of wear.

Frequently Asked Questions

How long does it take to break in a generator?

Breaking in a generator the right way could take six to eight hours. There are several steps to ensure that the engine is adequately lubricated and any residual debris clears and operating the generator with a moderate load before regular use.

Is there a break-in period for a new generator?

Yes, every new generator should follow the steps to break in the engine properly. These include:  1) reading the operator’s manual, 2) adding fuel and oil, 3) running the engine at least twice with oil changes to seat the pistons and clear any metal debris, and 4) running the engine a third time with a load.

Should you give the generator a rest?

If you have a gasoline generator, you will need to stop it to refuel (as you should never add fuel while the engine is running or hot to avoid potential fire hazards). Allow five to ten minutes for the engine to cool before adding gasoline.

A generator engine is a machine designed to run as long as it has fuel and proper lubrication. You should stop the engine before adding fuel and allow time for visual checks of the generator in general.

Should I break in a generator more than once?

If you have followed the proper steps to break in the engine, there should be no need to repeat the process.

Can I start my generator without breaking it in?

After filling the oil reservoir and gas tank, you can start the generator. However, failing to follow the steps to lubricate the engine’s moving parts can shorten its lifespan and cause irreparable damage to some of its engine parts.


If you want your new generator to last several years, it is highly advisable to use the steps listed in this article to break it in properly. Although it may take several hours to go through the process, the return on your time will be well worth it as you enjoy many hours of use through the years.

About Chad & Rick

Chad and Rick are the father son team behind Generator Hero. Rick is an engineer and manager, he’s used generators his whole life and specializes in fact checking our articles. Chad is a writer and webmaster helping to keep things running smoothly on the site. Read more about Rick and Chad, or send a message using this contact form.

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