3 Best Diesel Generator – Reviews & Buyers Guide


Diesel powered generators are not the most common type available, but they are a good alternative to conventional portable gasoline powered generators. Like cars, a diesel-powered generator is more economical in terms of fuel, which is just one of the advantages of this alternative.

So how does a diesel generator compare to a gas generator and how do you decide which one best meets your electrical needs? Here is a buying guide to help you make the smartest choice, including three of the best options you can order today.

Our Top Pick

Last update on 2022-07-06 / Affiliate links / Images from Amazon Product Advertising API

Top 10 Best Diesel Generator To Buy In 2021

Last update on 2022-07-06 / Affiliate links / Images from Amazon Product Advertising API

10 Best Diesel Generator Review

Bestseller No. 1
Generac 6864, 5000 Running Watts/5500 Starting Watts, Diesel Powered Portable Generator
  • Durable, fully welded 1 1/4" steel frame
  • Yanmar LW Series 435cc air-cooled direct injection, industrial-grade diesel engine
  • Diesel power requires less maintenance, is more efficient, and provides a long life
  • True Power Technology provides less than 5% total harmonic distortion for clean, smooth operation of sensitive electronics, tools and appliances
  • True Power Technology provides less than 5% total harmonic distortion for clean, smooth operation of sensitive electronics, tools and appliances
Bestseller No. 2
TBVECHI Diesel Engine, 4 Stroke 10HP Diesel Motor Engine Heavy Duty Single Cylinder Air- Cooled Recoil 3600RPM, Single Cylinder Air Cooled Machine
  • 【Engine Product Parameters】Displacement Capacity(CC): 406CC; Speed(rpm): 3600 rpm; Max.output(kw): 6.3; Fuel: 0#diesel oil; Fuel Oil Tank Volume(L): 5.5 L; Fuel Oil Consumption rate(g/kw.h): ≤280; Starting System: Recoil; Engine Cooling Type: Forced Air Cooling.
  • 【Reliable and Powerful Design】Single cylinder air cooled machine through advanced software analysis and optimization design, the reliability of diesel engine in structure and cooling is ensured.
  • 【Wide Application】Machine is widely used in small agricultural machinery, such as micro-tiller, pastoral management machine, irrigation and drainage machine, generator set, small transport vehicle, small walking tractor and other fields.
  • 【Energy Saving】Optimize fuel system and intake and exhaust system to save energy and fuel. Compact structure, small size and light weight. Large capacity fuel tank, Enhanced thickening, large fuel tank volume, special painting process.
  • 【Guaranteed】This item will ship from USA, delivery time need about 5-8 days. If there is any questions please feel free to contact with us, our experienced TBVECHI customer service team will response in 24 hours. If you’re not 100% satisfied with your purchase, we will provide a money-back guarantee.
Bestseller No. 3
WEN DF1100T 11,000-Watt 120V/240V Dual Fuel Portable Generator with Wheel Kit and Electric Start - CARB Compliant, Black
  • Switch between gasoline (11,000 surge watts, 8,300 running watt) and propane (9,500 surge, 7,500 running) with the simple turn of the selection dial
  • Voltage easily goes from 120V to 240V, perfect for transfer switches and emergency backup
  • Electric start powers the 457cc 4-stroke OHV engine with the turn of a key
  • 6.6-gallon tank provides up to 8.5 hours of half load run time
  • Includes four 120V GFCI outlets (5-20R), a 120V 30A twist lock outlet (L5-30R), a 120V/240V 50A outlet (NEMA 14-50R), a 12V DC cigarette-lighter-style plug, a bottle of oil, a 47-inch LPG connection hose, and a two-year warranty
Bestseller No. 4
Honda EU2200i 2200-Watt 120-Volt Super Quiet Portable Inverter Generator with CO-Minder - 49-State
  • More Power. Same Legendary Quality. - The EU2200i delivers 10% more power than the previous EU2000i - enabling you to power more of what you need, in the same lightweight, compact package. The EU2200i gives you the power to get more done.
  • Co-minder - Advanced Carbon Monoxide Detection System. CO-MINDER continuously monitors carbon monoxide (CO) levels. It automatically shuts down the generator before detected CO levels near the generator become dangerously high.
  • Honda My Generator App + Bluetooth Capability - Honda's exclusive My Generator smartphone app offers remote generator operation and monitoring with impressive performance. The app includes wireless stop and operation monitoring.
  • Lightweight And Compact - Weighing just over 47 pounds, the EU2200i is incredibly lightweight and portable. Thanks to Honda's inverter technology, it's easy to transport and store.
  • Commercial Grade Reliability - The EU2200i is powered by the Honda GXR120 Commercial Series engine. At 121cc, the GXR120 is at the top of its class - ensuring the EU2200 always produces the power you need to get the job done.
Bestseller No. 5
WEN GN400i RV-Ready 4000-Watt Open Frame Inverter Generator, CARB Compliant, Black/orange
  • Dimensions: 19.8" L x 13.8" W x 18.9" H | Weight: 66.1 lb
  • Generate clean power to safely operate sensitive electronics such as phones, tablets, televisions and computers
  • Parallel-ready panel allows you to connect any two WEN inverter generators for increased wattage output
  • 212cc 4-stroke CARB-compliant OHV engine produces 4000 surge watts and 3500 rated watts
  • Includes two 120V NEMA 5-20R receptacles, two 5V USB ports, one 120V RV-ready TT-30R receptacle
Bestseller No. 6
WEN DF475T Dual Fuel 120V/240V Portable Generator with Electric Start Transfer Switch Ready, 4750-Watt, CARB Compliant
  • Switch between gasoline (4750 surge watts, 3800 running watt) and propane (4350 surge, 3500 running) with the simple turn of the selection dial
  • Voltage easily goes from 120V to 240V, perfect for transfer switches and emergency backup
  • Electric start powers the 224cc 4-stroke OHV engine with the turn of a key
  • 4-gallon tank provides up to 11 hours of half load run time
  • Includes two 120V GFCI outlets (5-20R), a 120V/240V NEMA 30A twist lock (L14-30R), a 12V DC cigarette-lighter-style plug, a bottle of oil, a wheel and handle kit, a 47-inch LPG connection hose, and a 2-year warranty
Bestseller No. 7
Generac Guardian 24kW Home Standby Generator with PWRview Transfer Switch Wi-Fi Enabled
  • Save up to 8,000 dollars in product and installation costs (when compared to competitive output products)
  • Takes up 70% less space (when compared to competitive output products)
  • PWRview, Generac's home energy management system, allows generator owners to monitor and manage home energy usage, leading to a reduction in electric utility bills of up to 20%
  • Using PWRview you could save enough to pay for your generator
SaleBestseller No. 8
Westinghouse WGen9500DF Dual Fuel Home Backup Portable Generator, 12500 Peak Watts & 9500 Rated Watts, Remote Electric Start, Transfer Switch Ready, Gas and Propane Powered, CARB Compliant
  • 9500 Running Watts and 12500 Peak Watts (Gasoline); 8500 Running Watts, 11200 Peak Watts (Propane); Remote Start With Included Key Fob, Electric and Recoil Start; Up to 12 Hours of Run Time on a 6. 6 Gallon Fuel Tank With Fuel Gauge
  • Features Two GFCI 120V 5–20R Standard Household Receptacle, One Transfer Switch Ready 120V L14-30R, and One RV Ready 120/240V 14–50R; All Outlets Have Rubber Covers for Added Safety
  • Powered by a Heavy Duty 457cc Westinghouse 4-Stroke OHV Engine Featuring a Long-Lasting Cast Iron Sleeve With Automatic Low Oil Shutdown and Digital Hour Meter. VFT display gives you real time updates with the voltage output, frequency, and lifetime hours
  • Plug-and-Play: Comes With a Remote Start Key Fob, 12V Battery Charger, Oil, an Oil Funnel, a Tool Kit, and a User’s Manual to Get You Started Right Out of the Box (Minimal Assembly Required)
  • All Westinghouse Portable Generators are Functionally Tested in the Factory and May Contain Minimum Residual Oil and/or Fuel Odor; EPA and CARB Compliant; Backed by 3-Year Limited Service, Labor, and Parts Coverage with Nationwide Customer Service Network
Bestseller No. 9
Champion Power Equipment 100111 15,000/12,000-Watt Portable Generator with Electric Start and Lift Hook
  • Ultra-Powerful – At 15,000 starting watts and 12,000 running watts, enjoy up to 9 hours of run time on a full tank of gasoline with a noise level of 78 dBA from 23 feet
  • Electric Start – Trust the reliable 717cc V-Twin Champion engine with its battery-included electric start featuring a reliable toggle switch, plus built-in Cold Start Technology for easy starts in cold weather
  • Covered Outlets – One 120V 30A locking, a 120/240V 30A locking, a 120/240V 50A and four 120V 20A GFCI outlets, plus Volt Guard built-in surge protector prevents overloads and keeps your appliances and equipment safe
  • Lift Hook – Designed for safe and easy transport, loading and unloading, plus the Intelligauge keeps track of voltage, hertz and run-time hours so you can easily monitor power output and track maintenance intervals
  • Champion Support – includes 3-year limited warranty with FREE lifetime technical support from dedicated experts
Bestseller No. 10
WEN 56203i Super Quiet 2000-Watt Portable Inverter Generator w/Fuel Shut Off, CARB Compliant, Ultra Lightweight
  • Ultralight body weighs in at a mere 39 pounds for easy transport and storage
  • Extremely quiet operation comparable to the sound of a normal conversation according to the US Department of Health and Human Services
  • Produces 2000 surge watts and 1700 rated watts of clean power for safe charging of sensitive electronics (phones, tablets, televisions, computers, etc.)
  • Fuel shutoff maximizes the generator’s lifespan by using up the remaining fuel in the carburetor before shutting down
  • Includes two three-prong 120V receptacles, one 12V DC receptacle, two 5V USB ports, and a two-year warranty

Last update on 2022-07-06 / Affiliate links / Images from Amazon Product Advertising API

Things to Consider

When it comes to buying a diesel generator, the price is not the only determining factor. There is a whole bunch of things to consider when picking a diesel generator depending on what exactly you want to use the diesel generator for. Also, get to know the reason why you are getting a diesel generator, this could be as a result of the fuel easily obtained wherever you may be.

Pros and cons of diesel generators

There is very low maintenance cost associated with the use of the diesel generators. This is due to the fact that the diesel generators lack the presence of spark plugs and carburetors. This means no spark plugs to replace as well as no carburetors to rebuild. The major maintenance required for the diesel generator is the oil change and if done regularly will make your diesel generator last very long without any major maintenance being required.

It is also observed with diesel generators that they tend to outlast the gasoline generators when performing the same amount of work. They do the same workload and do not burn as much fuel as the gas generators. The fuel itself is also lower priced when compared to gasoline and propane fuel. In terms of a lifetime, the diesel generator is much longer lasting than the gasoline generator.

The typical gasoline generator will last approximately 1000 hours if that much. However, the diesel generator will last 30,000 hours on average without requiring a major overhauling. The diesel generator is built to withstand pressure and run at half the speed of the gasoline generators that are built mainly for intermittent usage.

Diesel and Gasoline Generators Comparison

Diesel fuel is also much better to store than gasoline. It is flammable, but it is not as great a risk as gasoline can be explosive. The exhaust of the diesel engine is, in fact, more visible, and this is considered one of the major downfalls of diesel as a fuel. However, if the diesel generator is properly maintained, there will be no need to be concerned as the exhaust will be minimally visible only when the generator is pressured under load changes that are severe.

Diesel can be very noisy, and this is considered to be a great downfall of the diesel system. This is usually one of the reasons homeowners tend to opt for gasoline generators. The gasoline generator is much less noisy than the diesel generator, and therefore there is no need for the generator to be placed far away from houses.

There are other options available now such as soundproof enclosures that can assist with this issue. Another consideration is the initial costs involved in setting up the diesel generator. This is usually quite a bit higher than the gasoline generator. It can be seen however that the diesel generator costs, when compared over a few years, is much less than the gasoline generator.

The choice of whether to opt for a diesel or gasoline generator can be assessed in terms of usage. If the generator is to be for intermittent use, a gasoline generator may not be a bad purchase, but overall it is considered that the diesel generator is more economical. The pros of the diesel generator by far outweigh the cons making it the better buy.

What to look for in an ideal diesel generator?

As we mentioned above, the major features of diesel generators are pretty much the same as other generator types. Let’s discuss them in more detail.

Powerful Engine

The power of the engine of any diesel generator is to be noted because of the amount of load the engine can carry depends solely on the power generated in the engine. In most cases where a particular diesel engine generates less power than required, it becomes so frustrating for the user and may lead to damage to the diesel generator.  A four-cycle engine is the best to consider because it allows smooth operation in diesel generators.

Output power and fuel consumption

The output power refers to the amount of power that can be supplied to the electrical appliances connected to the diesel generator. The higher the output power, the more electrical machines or appliances can be used with the diesel generator. The output power is measured in Watts, and this makes it easily noticeable in the product descriptions of diesel generators.

The fuel consumption of diesel generators differs from manufacturer to manufacturer making calculating a standard measurement difficult, but in general, fuel consumption of diesel generators determines the rate at which diesel is used during machine operation. The higher the load on a particular diesel generator, the higher the rate of fuel consumption as very little load does not take too much fuel. The fuel injection system into the engine goes a long way in determining the level of fuel consumption of a diesel generator.

Quiet work

Many consumers cherish the noiseless feature in a diesel generator, and this makes it necessary in some way for diesel generators to be as quiet as possible during operation. Some diesel generators come with a soundproof feature thanks to a noiseless muffler system that enables little or no noise at all during operation. Example of such a generator that has a quiet work operation like this is the DuroStar DS7000Q diesel generator.

Types of Generators

There are three main types of generators: portable, inverter and standby. Despite their differences, all of these generators should undergo similar generator maintenance to ensure long-term use.

Portable Generator

A portable generator is powered by gas or diesel fuel and can provide temporary electrical power.

Here are some characteristics to note about these types of generators:

  • Uses a combustion engine to conduct electricity.
  • Can plug into electrical appliances or tools via its sockets.
  • Can be wired into a facility’s subpanels.
  • Can be used in remote sites.
  • Has enough power to run a television, freezer and refrigerator.
  • The engine should run at 3600 rpm to render the standard 60hz of current.
  • Use a governor to control the engine’s speed.
  • Can power tools and lights.

Inverter Generator

An inverter generator uses an engine connected to an alternator to produce AC power. It also uses a rectifier unlike other generators to convert the AC power into DC power.

Here are some characteristics to note about these types of generators:

  • Relies on high-tech magnets.
  • Uses advanced electronic circuitry.
  • Undergoes three phases to produce electricity.
  • Outputs AC current, convert it to DC current and finally invert it to AC.
  • Maintains a constant flowing of current to an appliance.
  • Is more energy-efficient, as the engine speed adjusts itself according to how much power is needed.
  • Its AC can be set to any voltage and frequency when used with proper equipment.
  • Tends to be little and lightweight.
  • Can fit into a car, RV or boat.

Standby Generator

A standby generator is an electrical system that operates with an automatic transfer switch that commands it to power a device up during power loss.

Here are some characteristics to note about these types of generators:

  • Operates automatically.
  • Delivers permanent power protection.
  • Has two components: a standby generator and an automatic transfer switch.
  • Can operate on liquid propane or natural gas.
  • Will run on the fuel type already in use in the facility or home.
  • Uses an internal combustion engine.
  • Senses the power loss within seconds and boots up electricity so that power loss is felt very briefly.
  • Executes automatic weekly self-tests to see that it is properly reacting to a power loss.
  • Is constantly monitoring utility power.
  • Used in safety systems for elevators, standby lighting, medical and life support equipment and fire protection systems.

Best Generator for Different Outages

Generator TypeBest Use
Portable GeneratorRefrigerators, spray gun systems, nail guns
Inverter GeneratorCar batteries, laptops
Standby GeneratorEmergency settings, hospital machinery

Generator Maintenance

Maintaining a generator is a relatively similar process among the three major types of engines. First, it is vital to follow the maintenance schedule of the manufacturer with each type of generator. A routine maintenance practice is that of general inspection. Inspections consist of checking for leaks, assessing oil and coolant levels, glancing at the belts and hoses and checking the battery terminals and cables.

It is important to inspect the oil as well, as it must be changed regularly. Oil change frequency depends on the manufacturer, how often the generator is used and your work environment. Typically, it is recommended you change the oil after 100 hours of operation, especially if the generator uses diesel.

Generator maintenance requires:

  • Annual fuel cleaning and filtering, as diesel fuel degrades quickly. After a few weeks of operation, diesel fuel degrades via contamination of water and microbes, resulting in clogged fuel lines and filters. Fuel cleaning involves using biocides annually in all generators except for the standby generator, in which it will attract moisture.
  • The cooling system to be maintained, which requires checking the coolant level at existing intervals. This must be done during shutdown periods.
  • Checking for battery power; this is especially true for standby generators, as battery issues are their primary cause of failure. Make sure the batteries are robust and charged enough to last long so as to not incur any start-up hitches for the generator.
  • Regular testing to inform of the battery’s current status. Testing involves checking the electrolyte levels and specific gravity of the batteries. The batteries themselves also must be clean.

Further Care and Maintenance of Generators

Besides the above best practices, it is also important to exorcise the generator on a weekly basis for 30 minutes under load. This will charge the battery, remove excess wetness, lubricate the engine and filter the fuel and foil. Any loose pieces found anywhere on the generator must be placed securely in.

You should also keep records of inspections and tests for future inspections and scrutiny. These records will allow you to stay in the know of your generator’s state.

Buyer’s Guide & Frequently Asked Questions

Before buying a diesel-powered portable generator, you might want to learn a little bit more about how these generators work.

You also might want to gain a better understanding of how these generators compare.

While I have my own favorite, I know that not every generator is right for every person or their needs.

To help you find the right generator for you, you may want to consider the following questions.

Which diesel generator do you recommend for home use, as a backup power source?

My recommendation for a diesel backup power source is the DuroStar DS7000Q. It offers a good amount of power, the outlets you need, and the best overall value.

The pricier Generac 6864 is a better choice for people who need a long runtime.

If your power loss lasts for a while, it can get frustrating quickly to keep refilling the fuel tank. The Generac will last for more than 24 hours at a half-load. If you might be looking at a power loss of several days or live in an at has regular switches, the Generac is probably the smarter choice.

Which oil to use in a diesel generator?

You should always use the oil recommended in the generator’s manual. For the Generac 6864, for example, the recommended oil type is SAE 10W-30.That oil is probably a safe bet for all diesel generators, but you should definitely check the manual to make sure. As the Pulsar manual points out, the correct oil type should account for the current ambient air temperature.

For colder temperatures, you’ll want to use an oil with a lower viscosity like 5W-20. For really hot temperatures, you’ll want to use an oil with a higher viscosity, like SAE 40.

Regardless of which oil type you use, it’s very important that you follow all the oil-related maintenance tasks as laid out in the manual for your diesel generator. Generally, this includes checking the oil regularly, usually before every start.

You’ll also have to change the oil fully after so many hours of use. Some of the generators on this list include an indicator on the control panel that alerts you when you need to do this. Failure to follow the manual’s maintenance instructions could mean your generator won’t last as long, which could even void the warranty.

What is the smallest diesel generator?

These generators are all around the same size, which is to say not huge but a bit bulky.The smallest one of this list is the Generac, which measures 38 x 22 x 25 inches.

That said, it weighs around 250 pounds, so it’s not the lightest option. The Gilette is quite a bit larger but only weighs 200 pounds. If you’re concerned about the size for storage purposes when it’s not in use, the Generac is your best bet.

If you’re thinking instead of how easy it will be to move around, you should consider other things as well.

These include the weight, frame design, whether it is enclosed or open, whether or not it has handles, and if a wheel kit is included. Think about how you will be using the generator and whether or not you’ll need to transport it from place to place regularly.

If you foresee a lot of transport, you should think about which one will be easiest to transport.

How does diesel compare to propane or gasoline-powered portable generators?

One major advantage that diesel generators have over gas generators is fuel efficiency.It takes less fuel overall to run a diesel machine.

All engines need a combination of fuel and air to run. This is because a diesel-powered engine compresses air before ignition instead of a gas engine that mixes fuel and air first.

The compression of a diesel engine results in much better fuel efficiency. This means that diesel engines will run for longer in addition to needing less fuel. If you are running your generator pretty consistently, a diesel generator will cost less to operate over the long run than a gas generator, just based on fuel cost alone.

When comparing a diesel generator to a propane generator, these differences are even starker. A propane engine will use about three times the fuel of a diesel engine.

In addition to being cheaper to run, diesel also has the advantage of being the least flammable fuel type. In certain kinds of natural disasters, this is especially important.

Another advantage diesel generators have over gas generators is their life expectancy.

Because gas generators tend to run much hotter than diesel generators, they tend to die and need to be repaired or replaced sooner. Diesel generators need regular maintenance a bit less often. One reason for this is that they have no carburetors or spark plugs.

A disadvantage of diesel over gas and propane is that diesel generators tend to be a bit noisier.

That said, diesel generators have gotten much quieter than they used to be. The Pulsar generator, in particular, is just as quiet as many portable gas generators. Some of the other generators on this list have open frames. This has certain advantages but also comes with the downside of being louder.

A disadvantage of both gasoline and diesel, when compared to propane, is that the exhaust is not clean-burning. Propane has a lower environmental impact as it is a clean-burning fuel source.


Diesel generators can be great tools to have on hand, especially for use as a home backup in a power loss situation. Have you ever used a fuel-efficient diesel-powered generator? What did you think?  Which one of these models do you have your eye on?  Let me know in the comments! Feel free to ask any questions you might have about diesel generators as well.

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