+86 13073847729

Mon - Fri 08:30 - 17:00

No.1515, Fengnan East Road, Jiaojiang, China


12Dec 2022

How to change the oil in a generator: A step-by-step guide

table of contents

To ensure the normal operation of the generator without failure, its maintenance is essential. The most critical step in generator maintenance is to replace the generator oil.

BISON generator manufacturer is strongly advises that you keep a close eye on the generator's oil level. Not changing the oil when needed, or lowering the oil level in the generator, which is not only affect the electric generator's performance but can also cause massive or even permanent damage.

Therefore, to avoid encountering such situations, it is recommended that you regularly check and change the generator oil. Simply following those simple steps will allow you to change your oil quickly.

Let's get started and see the steps required to change petrol generator oil:

Step-by-step instructions to change generator oil.jpg

BISON change generator oil step-by-step instructions

Step 1 : Prepare all the essential required to change the generator oil

Before starting the process, it's a good idea to have your generator oil change gear ready. like manufacturer's recommended oil, protective gloves and goggles, oil funnel and so on.

Step 2 : Warming engine oil

Cold and old engine oils tend to be sticky, and given that, some deposits in them will settle to the engine's bottom. To ensure that all oil and dirt are drained, you should warm up the engine for about 10 minutes. To do this, you need to run the engine at about 50% load for 10 minutes, then shut it down.

Step 3 : Place the generator on a slightly higher level surface (if possible)

Changing the generator oil while leaving the generator on the floor can be tiring. One has to bend a lot and maybe  straining the back. Therefore, a helpful tip is to place BISON generator on a slightly higher level surface before starting work. For example, take four identical blocks and place them on the surface where you want the generator to be placed. After placing the block, carefully lift the generator and put it on the block. Make sure the blocks can take the generator's weight, and the generator is levelled correctly.

If the generator is bigger, like quiet diesel generator, inverter generator, you obviously can't move it. In that case, you have to bend sometimes, but you can take a break during the oil change.

Step 4 : Removing the generator spark wires

Now is the time to remove the generator spark wire. In some BISON generator models, the spark wire is easy to locate. However, in some models, it is hidden under the generator cover. Check the generator's owner's manual in advance to confirm the location.

Once you've located the spark wire, grab it and simultaneously pull and twist it. You can remove and unplug the spark wire with some effort.


Step 5 : Draining the old oil

Need to remove the drain plug. Usually, the oil drain plug has a hexagonal lid. If you see some stains or oil around or on the plug, remove it with a cloth or damp towel. After removed the drain plug, the oil will start pouring out of the generator.

Step 6 : Change the oil filter

Many people just removing the oil and forget to change the oil filter. Changing the oil filter at the same time saves money and helps the BISON generator run longer.

The oil filter can be changed using a standard wrench or a unique tool designed for this purpose. Hold the oil filter with a wrench and twist it gently to loosen it slightly.

Once loose, you can manually unscrew it until it finally comes out. Insert new filter, slowly insert and tighten into place.

Step 7 : Insert generator's drain plug

Step 8 : Pour the oil

The funnel will ensure the oil doesn't spill anywhere and can be easily added to BISON generator. To make sure you're using the correct type of oil, you have to read your generator's owner's manual.

Also, make sure to keep an eye on the oil level, generator oil should not be below or above the mark.

Pour the oil.jpg

Step 9 : Insert the spark Plug

After pouring the oil, put sparke plug back properly.

Step 10 : Starting the generator

The final step in changing BISON generator oil is to start the generator and let it run for a few minutes. This step helps lubricate the generator and ensures the new oil flows correctly through the generator.

After a few minutes, please turn off the generator and recheck the generator oil level to make sure it is still within the recommended oil level range. If not, please adding more oil to attain the required level.

Purpose of generator oil

  • Sealing: The oil forms a sealing between the piston ring and the piston to reduce gas leakage and prevent external pollutants from entering.

  • Anti-rusting: The lubricating oil can be adsorbed on the surface of the parts to prevent water, air, acidic substances, and harmful gases from contacting the parts.

  • Lubrication: Between the piston and the cylinder, as well as between the main shaft and the bearing bush, there is rapid relative sliding. An oil film must be formed between the two sliding surfaces to prevent excessive wear of the parts. An oil film of sufficient thickness separates the surfaces of the opposing sliding parts to reduce wear.

  • Cleaning: Good engine oil can bring the sludge, carbide, and worn metal particles on the engine parts back to the oil tank and wash the dirt generated on the working surface of the parts through the flow of lubricating oil.

  • Cooling: The oil can bring the heat back to the fuel tank and then dissipate it into the air to help the fuel tank cool down.

Purpose of generator oil.jpg


Is it necessary to check oil level is correct?

Without oil, BISON generator will stop working, leaving your operations in the dark and equipment idle until the generator is replaced. This is a costly and completely avoidable situation. Here are the times you want to check that the oil level is correct.

  • After installation and during break-in

A large number of China generators are shipped without oil in the system. Confirm if your new generator comes with oil or if you need to add oil after installation. 

Again, you need to change the oil as soon as the break-in process begins. During a break-in, debris and particulates are drawn into the oil flow and circulate in the engine. Changing the oil after the manufacturer's specified break-in hours helps protect the engine from damage.

  • After any major failure

It may appear unconnected, but many BISON generator failures result from problems with the oil system. Power spikes and interruptions can occur when dirty oil prevents the motor from running smoothly. When any loss occurs, test the oil to see if it is full of debris and check the filter to ensure it filters the oil properly.

  • After a major spill

Your generator should automatically shut down if the oil level falls below safe operating levels, which is usually the first sign of a major leak. For most generators, BISON recommended to repair the leak before changing the oil to ensure that any contaminants that may have entered the system are flushed out before returning to service.

  • After a period of heavy generator use

Whether you're experiencing peak production or because a significant problem with the grid forces you to rely on your generator more than usual, you should change your oil after heavy use. This will help protect the engine and ensure smooth operation when you return to normal operation.

  • Within the time interval recommended by the manufacturer

Oil changes are often overlooked. However, they should be incorporated into your routine maintenance schedule. Keep an accurate log of generator usage and do not exceed the manufacturer's recommendations. Not only is this unsafe, but it will void any warranty you have on your generator.

why engine oil deterioration?

BISON believes that the five main reasons for the rapid deterioration of oil are as follows:

  • The quality of the oil is not up to standard.

  • The technical conditions of the generator set are not good.

  • The generator often runs at low load, low temperature, and low speed, the piston deformation is insufficient, and the combustion is not good. Diesel enters the oil sump along the cylinder wall, diluting and deteriorating the oil.

  • The exhaust gas enters the oil sump and condenses into acidic substances and moisture, deteriorating the oil.

  • The oil filter is dirty, and the unfiltered dirty oil enters the lubricating part, which also accelerates the wear of the generator parts.

How much time it takes to change the generator oil?

The oil changing process for most generators takes one to two hours.

Can I use synthetic oil in my generator?

Using synthetic oil in generators is not a problem, although you must check the manufacturer's recommendations. Synthetic motor oils have a chemical composition that protects and lubricates the engine more effectively.

However, ensure you don't use single-grade or multi-grade oil as it can damage the generator's engine.

How to properly dispose of old oil?

After changing the generator oil, you need to dispose of the used oil. However, you can't just throw old oil anywhere you like.

Oil can be highly damaging to the environment. It contaminates soil and water bodies. Also, you can't even throw it in your trash.

Find a hazardous waste facility in your area that collects and recycles used motor oil. You can also contact your local auto repair shop, as many auto repair shops collect used oil for various purposes.

Disposal of used oil anywhere other than the above is not permitted by law.

In conclusion

Now that you have the knowledge on how to change generator oil, you can do it regularly! You can always rely on BISON generator to power your tools and equipment. Just be sure to check the manufacturer's manual for advice on the type of oil and filter needed, how much oil is required, and how often it needs to be changed.

When it's time to change the oil for your generator, you can rely on BISON manufacturers to guide you. We invite you to contact BISON machinery for more information on oil changes and our generator maintenance program.

inquiry form here


BISON BLOG, All the latest news and views from Bison Machinery.

what's hot?

Everything you need to know about plate compactor Open Frame vs Closed Frame Generators: What's the Difference? Generator Backfires Trowel machines: Introduction, types, working mechanism and buying guide

Related Products