Rankedgenerators is audience-supported. When you buy through links on this site, we may earn an affiliate commission that we use for site maintenance. Learn more


How to Break in a New Generator? – Ultimate Guide

How to Break in a New Generator
Written by Jamie Masterson

The generator you ordered has arrived. Before you start thinking about your next camping trip, there is one important step first – to break the generator in.

There’s a possibility that your portable generator’s lifespan will be affected by the first few hours you use it. You should do it correctly to get the most from your investment.

Here we’ll discuss what exactly breaking in a generator means and why we need to do it!

How to Break in a Generator?

Step 1: Buy the required items


Use a funnel to make pouring the fuel in easier. This will help avoid splashing the fuel in unwanted places.


The manufacturer should recommend the most suitable engine oil type and brand. If you purchased your generator online, you can call the customer support hotline. They can help you with the recommended oil brand.

Buy good quality petrol fuel if possible. Of course, the price will be higher but it is better for the engine.

Oil conditioner

Oil conditioners are necessary to prevent oil from sticking to the engine cylinders. When the unit isn’t used for some time, this keeps the engine well lubricated.

You can prevent dry starts by using the oil conditioner.

Step 2: Lubricate

Lubricate the engine cylinders first to avoid dry starts. Disconnect the spark plug. Pour some oil conditioner into the spark plug chamber with a funnel.

Make sure the engine cylinders are lubricated before starting the generator.

Step 3: Pour the oil

Pour the recommended amount of engine oil through a funnel. If you aren’t sure how much oil to use, consult the user manual or get in touch with the manufacturer.

Step 4: Fill the tank with gasoline

Fuel the generator by filling the tank with gasoline. When possible, use high-octane fuel.

After you have added fuel to your petrol generator, start it. In general, it is normal for the generator to start slowly during the first or second pull. Keep trying until the engine starts.

Step 5: Run for an hour

Start the generator and let it run for an hour. Set the speed to the lowest possible setting. Don’t load anything into your generator.

Keep the engine running without any load for one hour.

Step 6: Drain the oil

The generator should get shut down after one hour. Drain and replace the oil. It is vital to change the oil after the first hour of running since this helps remove any broken metal pieces.

Then add oil conditioner and fresh oil once the first oil has drained out completely.

Step 7: Run for another hour

Restart your engine and allow it to run for an extra hour. Make sure the generator is not connected to anything. Keep it running without any load for another hour.

Step 8: Run it the last time

This is the third time you’re starting your generator. During the last hour, the generator can run from 500W to 1000W for one hour.

Why does your generator need breaking in?

Generation of brake mean effective pressure (BMEP)

Your new machine generates BMEP when you switch it on for the first time. Then, fuel and air are controlled to create an explosion in the combustion chamber.

It works by shaping and conforming to your generator’s combustion chamber. The BMEP pushes the piston rings against the walls of the cylinder.

This pressure is enough to drive the pistons against the walls unless there is a slight load on the generator. However, if there is even a slight load, this pressure no longer suffices.

The blow-by phenomenon can result in hot combustion gasses trickling into the crankcase. This can also damage the functionality of the unit!

Wearing the piston rings and cylinders

Cross-hatched cylinder walls on the new generator hold lubricant between the piston ring’s textured surface and the cylinder wall. This occurs when the piston rises and falls in the working engine.

While breaking in, the piston will wear into the cylinder wall. This alters the grooves of the piston ring face and cylinder walls. As a result, oil is deposited on both surfaces, which creates a film that enhances oil distribution.

Quick tips for breaking in a generator

  • Clean out any dirt
  • Check the recommended oil type and fill the oil reservoir
  • Add the recommended fuel to the generator’s fuel tank
  • Consult your owner’s manual for the frequency of oil change
  • Find out how often you need to change the oil


Q. Can I start my generator without breaking it in?

Not lubricating the engine’s moving parts can reduce the generator’s life. This is the same when metal debris is not removed, causing irreparable damage to some parts.

Q. How long can my generator run without a break?

Taking proper precautions will allow you to run your generator for a maximum of 12-18 hours

Q. Does a generator need breaking in more than once?

If your first attempt is successful, there’s no need to break in the generator more than once.

Q. When will my generator be ready to use?

You can safely use a generator after you have completed each step of the break-in process. Go ahead and power sensitive electronics, tools, and appliances in your home.

About the author

Jamie Masterson

With decade-long experience as a generator technician, Jamie has worked with USA’s top generator manufacturers and suppliers as an independent contractor.

The long years of service to the industry has taught Jamie the ins and outs of troubleshooting, repairing, and maintaining all kinds of generators in home, industrial and outdoor settings.

Jamie thinks this platform is a great opportunity to share his tips and tricks with you so you can make the most of such power equipment for better living.

Leave a Comment