A portable diesel generator is a great solution for a temporary home backup as well as for use on remote sites.
When deciding between a gasoline, propane, or diesel portable generator, you’ll see different positives and negatives for each type.
The major advantage of a diesel generator is that it offers superior fuel efficiency which means you’ll get longer runtimes and spend less on fuel overall.
Before you go out and buy the first diesel generator you see or the cheapest one, it’s important to know that not every diesel-powered generator is reliable.
When you’re looking for a power source, you need reliability to be a baseline. All of the generators on this page are reliable. I’ve weeded out all the duds.
DuroStar DS7000Q - Dependable Power & Great Value
DuroStar generators are known for being dependable.
This 4-stroke single-cylinder direct-injection diesel engine is a beast that is ideal for backup use during a power outage.
It offers 6,000 peak watts and 5,500 running watts. Running this generator is easy. There are two different ways to start it up: a standard recoil start and an easy turn-key electric start.
Technically, there’s a third way that’s even easier because you can engage the electric start using a remote control.
The main panel has everything you need, including a low-oil alert light, a voltage meter, circuit breakers, a low fuel indicator, and power outlets.
There are two 120-volt, 20-amp, 3-prong outlets (with ground fault interrupter). These will work for all of your standard household appliances.
For high-powered tools like for use on a farm or worksite, there are two twist-lock outlets, one 120-volt, 30-amp, 3-prong outlet and one 120/240-volt, 30-amp, 4-prong outlet.
Diesel generators are known for being fairly loud but this one has some effective noise-reduction measures in place.
There is vibration-isolation mounting between the engine/alternator feet and base frame. This not only reduces the noisy vibration but it also extends the durability of the machine overall. There is also a very quiet muffler and some additional soundproofing.
The DS7000Q has a fairly long runtime. You can expect it to run for about 12 hours at a half load. It has a large 3.83-gallon fuel tank. There is a fuel gauge so you can keep an eye on how much fuel you have left.
Moving this generator around would be a challenge were it not for the wheel kit, as it weighs around 300 pounds. That said, the wheel kit makes it pretty easy to transport this generator.
Pros & Cons
Generac XD5000E - Cleaner Power, Longer Runtime
Generally, diesel generators are not inverters. This Generac machine isn’t either but it does offer cleaner power than many other diesel generators.
This is because of its True Power Technology which provides less than 5% total harmonic distortion.
That means the power is clean and smooth so you could probably even use this to power some of your sensitive electronics.
This generator runs on a Yanmar LW Series 435cc air-cooled direct injection, industrial-grade diesel engine. It offers 5,500 peak watts and 5,000 running watts.
This generator is very durable. It has a tough, fully-welded 1-1/4″ steel frame.
This frame is incredibly sturdy. It also is designed to make lifting for transport easier.
It’s pretty heavy at around 250 pounds but the frame design includes handles that make it much easier to lift.
You can also buy a wheel kit separately to make transport even easier.
If you want a long runtime, this might be the best diesel generator for you.
The huge 12-gallon fuel tank means that you can use this generator for just over 32 hours on a half-load.
Starting the generator is easy and you have a choice of either a recoil pull start or an easy push-button electric start.
Unfortunately, the battery is not included for the electric start. There also isn’t a remote start option.
The control panel includes an hour meter, a 120/240V selector switch, a 23-amp main circuit breaker, a 30-amp push-button circuit breaker, two 20-amp push-button circuit breakers, four 120-volt 20-amp outlets, and two 120-volt TwistLock outlets.
There is an automatic shutdown feature if the oil pressure gets too low. A compression release lever makes the generator easier to start in cold weather.
Pros & Cons
Gilette GEN-PRO GPED-65EK Diesel - Big Size & Big Power
This is the largest diesel generator on the list, measuring 48 x 48 x 48 inches. That said, it’s also the lightest, weighing only 200 pounds.
The steel frame is pretty sturdy and handles make it fairly easy to lift. To make transport even easier, you can buy a wheel kit separately.
This generator runs on a 9-HP, Kohler KD420 air-cooled, direct-injection engine.
The 4-gallon fuel tank will give you enough fuel to run for around 10 hours at a half-load. It features 6,500 peak watts and 5,000 running watts. A fuel gauge helps you keep an eye on when you need to refuel.
This generator has both a recoil pull start and an electric start. There is no remote start option.
You get 6 total outlets on this generator: four 15-Amp 120V (gfci) outlets, one 30-Amp 120V twist outlet, and one 50-Amp 120/240V outlet.
The control panel includes a voltmeter, an hour meter, and circuit breakers.
There is a low oil alert and an automatic shutdown feature to protect the engine.
Also on the control panel, there is a runtime meter and some service alert lights for alerting you when it’s time to change the oil, change the engine air filter, and service the engine.
Like most diesel generators, you can generally go longer in between required maintenance times than you would be able to on a gas generator.
Because of this, it’s really helpful to have these service indicator lights so you don’t have to keep track of how many hours you’ve run the generator.
Providing clean power, there is Power Assist. This is a Gillette-exclusive excitation system that uses a power capacitor and a unique winding design to ensure minimum power fluctuations.
This results in a harmonic disruption of less than 6%, making it safe for many smaller and more sensitive electronics.
Pros & Cons
Pulsar PG7000D - Cheapest Decent Diesel But a Riskier Buy
If you’re looking for the cheapest portable diesel generator worth considering, this is the one.
While you might find this model to be a decent fit for you, you will probably get what you pay for.
That is, you might be disappointed, especially longterm. A diesel generator is an investment but generally, it’s one that you will be able to use for a very long time.
With this model, that longevity is less certain.
This generator is known for having some problems. That said, some people have been happy with it and the price tag is certainly enticing.
This Pulsar machine runs on a 10-HP single cylinder, 4-Stroke, OHV, air-cooled engine.
It features 7,000 peak watts and 5,500 running watts. Starting it up is pretty easy and you have your choice of a standard recoil pull start or an electric push-button start.
This generator only gives you five total outlets: two 120V Outlets, one 120V/240V Twist Lock outlet, one 120V Twist Lock outlet, and one 12V 8.3AMP outlet.
The digital control panel includes a voltage meter and an hour meter.
Especially for a diesel generator, this unit is remarkably quiet.
This is thanks to the special consideration Pulsar took into effect regarding insulation, housing, and air flow.
They go so far as to call this line of generators their Silent Series. To say it’s actually silent is a stretch but it is one of the quietest diesel generators out there.
According to Pulsar, the total noise for this unit is less than 70dB. This is about as loud as a vacuum cleaner.
At a half-load, the 4-gallon fuel tank will last 9.5 hours. There is a fuel gauge to keep you aware of when you’ll need to fill up the tank.
This unit is pretty heavy at over 350 pounds. Wheels are included but there are no handles and the frame is fully enclosed. The lack of handles and the size of 38 x 32.5 x 22 inches makes it challenging to pick up and carry, even with two people.
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 the above generators compare.
While I have my own favorite, I know that not every generator is right for every person or for every need.
To help you find the right generator for you, you may want to consider the following questions.
Which do you recommend for home use (backup power source)?
My recommendation for a diesel backup power source is the DuroStar DS7000Q.
This is because it offers a good amount of power, the outlets you need, and it has the best overall value.
That said, the pricier Generac 6864 might be a better choice for some people. This is because it offers such a long runtime.
If your power loss lasts for a while, it can get frustrating pretty quickly to have 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 if you live in an area that has regular power losses, the Generac is probably the smarter choice.
Which oil to use?
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 for many diesel generators should take into account 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 task 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 as to when you need to do this. Failure to follow the maintenance instructions in the manual could mean your generator won’t last as long and it could even void the warranty.
What is the smallest sized 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 about how easy it will be to move around, you should consider other things as well.
These include the weight, the frame design and whether it is enclosed or open plus 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 regularly transport it from place to place.
If you foresee a lot of transport, you should think about which one will be easiest to transport.
How do they 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 as opposed to a gas engine which 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’ll be 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 have about three times the fuel consumption compared to a diesel engine.
In addition to being cheaper to run, diesel also has an 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 it also comes with the downside of being a bit 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.