Diesel generators v. Petrol generators: which is the best?

When it comes to engines, there's no greater grudge match then diesel generator versus petrol generator.

But this battle isn't restricted to the road - it's a battle that extends to, worksites, homes, businesses and farms across Australia. It's a battle of the generators.

Here at My Generator, we know for a fact that diesel generator are some of the most cost-effective and fuel-efficient units you can buy. But petrol generators have come of age and are taking on diesel generators at their own game. So who will reign supreme? We'll be the judge of that...

Diesel Generator Pros

For decades, people only knew diesel as a dirty, smelly truck fuel. But it's done a complete 180 to give petrol a run for its money - literally. Because one of the biggest advantages of diesel engines is their fuel efficiency. This comes down to the diesel motor's higher compression. So a like for like comparison of diesel generator and petrol generator will put the diesel ahead.

With diesel you also get a lower cost of ownership. That's why so many industries rely on diesel fuel to run their business, whether it's for generators, bulldozers, excavators or tractors. Diesel engines, and therefore diesel generators, last longer, cost less to run and take longer to depreciate in value. Why do they last longer? Because diesel engines don't have to work as hard as petrol engines to get the same power output. This means the engine parts are under less stress. Also diesel fuel is self-lubricating which means the fuel delivery system should last longer than that of a petrol engine - perfect if the generator hasn't been used for a while.

Diesel generator
Diesel Generators are often more efficient and require less maintenance than their petrol counterparts

Another thing that gives the diesel engine the upper hand is the lack of an ignition system. It simply doesn't need one, which means one less thing to fail. What's more, they can operate at loads between 60% to 100% for prolonged periods, which is an advantage over its petrol counterparts.

While you can find diesel generators powering smaller loads, such as domestic appliances for back up or DIY tasks, the advantages are best seen in more heavy industrial and mining applications. In fact, diesel generators are the backbone of the mining and construction industries.

A quality Mine Spec Generator will come with Safety and Protection features

Diesel Generator Cons

Diesel engines emit more noxious gases and CO2 per litre of fuel than petrol-powered engines. However, the upside is that because diesel engines use less fuel, they can also emit less CO2 over time. It all depends for how long you are using your generator. Cost is another factor. Traditionally, diesel has been more expensive than petrol - about 10% more in Australia. But the balance is certainly tipping.

Even though diesel generators last longer and are less likely to fail, they may be more expensive to fix when they do.

Petrol Generator Pros

Besides the cost of petrol being lower than diesel, there are a few pros for petrol. There is more choice of models for petrol generators. Like cars, this is because petrol generators have been around for longer. But that said, you'll find a growing selection of diesel generators for a whole range of applications and budgets these days; including home/business backup, trade/construction applications, solar set up backup, events and much more.

While diesel generator are lauded for their fuel efficiency, petrol generators are now being build with all kinds of economy modes and features to bridge the gap.

8kva Petrol Generator: for trade and farm use

Petrol Generator Cons

Petrol is much more volatile than diesel fuel. So if you're carrying lots of fuel for your generator, diesel is a safer option. Also, because of the way diesel engines work, they are much safer than petrol engines. There's no spark ignition, which means no risk of explosion and less maintenance than a petrol generator. At the same time, with petrol generators today, a whole variety of safety features and checks are incorporated to ensure this isn't an issue anyway.

Another downfall of petrol generators is that they reach a higher temperature than their diesel counterparts. This leads to more wear and tear on the generator parts over time, meaning more frequent maintenance and repair, and ultimately, a shortly life span. Consequently, petrol generators are not usually run at high loads for extended periods.

The verdict

It's a pretty close match...we say that if you are looking to use the generator for heavy commercial use, then diesel is probably the way to go. But if you are already operating other equipment with petrol, then a petrol generator can do the job also - when you consider leading Australian brands from the likes of Powerlite, Gentech, Dunlite or Crommelins they all have first rate options in both petrol and diesel. It really comes down to which model suits your application the best. Has this given you fuel for thought? Check out the full range of petrol and diesel generators at My Generator.

DISCLAIMER* Please note, this advice is general in nature and we strongly recommend consulting the product manual and where relevant, a professional installer.

13 thoughts on Diesel generators v. Petrol generators: which is the best?

20 August 2018
I need a switch (not pull) start generator to cover during mains blackouts. I have two pumps which may be used at the same time as generator will serve two dwellings. Pumps are Onga 110 2.3 amps and Onga 100 2.65 amps. usual domestic appliances. What can you recommend?

My Generator Response
Hi Genia, I spoke to Onga Australia and they said that the general rule of thumb is a start current of 4.5X the running current. I would recommend to go with a a good quality electric start generator of at least 6kva. be sure to start the larger pump first and wait until the pump is running for a little while before starting the second pump. We would recommend to use the Yamaha 6000w Petrol AVR Generator EF7200E Electric start Automatic Voltage Regulation 4 Year Warranty Feel free to give us a call on 1300 400 122 regards Paul

22 July 2018
It is Possible for anyone to be able to make their own free electrical power by simply building a Magnetic Energy Generator. The power companies building wind-powered generators on a grand scale of Generator Suppliers in Dubai.

15 July 2018
The OTC generators original and well-known brand engine to power our generators like global power machine in Generator Companies in UAE. The major parts and Machin item testing check to the quality assembly loaded works started. http://www.otcglobal.net/

29 April 2018
Hello My Generator, I need your guidence in buying a generator for Church purpose, and also for outdoor meetings. Requirement: It should support AC, almost 20 fans, lighting, and Powerful Soundsystem at a time. It should support water system too. One of my main concerns is that it should not be noisy. So, please suggest me to buy a generator which can satisfy my requirements.

My Generator Response
Hi James, thanks for your question. Ideally you would know the exact maxiumum power draw for all of your required appliances, then you can size the generator accordingly. The simplest way to do this is to engage an electrician who can take a power reading on your total required power draw of the Church (and anything else). This is a very simple exercise for an electrician / electrical contractor. However to give you an idea, two generator models that we have supplied for similar applications as you have described, are: - Yamaha 6300w Inverter Generator: this is a portable unit is on wheels making it easy to move around as required. Encased in sound proofing material, this generator is ultra quiet with a noise rating of 58 decibels at 7 metres. - Kubota 6kva Lowboy Diesel Generator: a stationary unit that is also designed for quiet operation, this model has a large fuel tank to allow prolonged operation. A larger Lowboy model is also available at 8.8kVA in size. Please feel free to give our team a call on 1300 400 122 to discuss further. Again, its best to know your specific max power draw. The above models are just examples; your particular requirement may need more or less power, which opens up the options to further silenced generator models to best suit your needs. Many thanks.

14 February 2018
Great comparation..for safety purposes diesel generator is best...

2 April 2017
Hi there, I'm looking at a generator to power our home during blackouts such as the one we have just experienced following cyclone Debbie here in QLD Australia. We need to power a large fridge, water system, minimal lighting and TV/laptops so we can keep up with local news broadcasts. Would a diesel be suitable for sensitive electronic equipment?

My Generator Response
Hi Taf, you've come to the right place. You have three main options in relation to types of generators (in both petrol or diesel) for your type of home backup power requirement. In terms of sizing, from what you've listed the only query would be the water system; water pumps can either be quite efficient or some can have significant start up (surge) requirements, so ideally you would know how much power your water pump system needs - often the best way is to get an electrician to take a meter reading on your home. Alternatively, for the main item in question, you can contact the pump manufacturer to get the maximum required power amount for your particular model. A large domestic fridge will typically require less than 2000 watts and your lights/TV/Laptops etc. will only draw a few hundred watts. So again, preferably you would know exactly how much power you need as you dont want to end up with a generator that is too small for your particular appliances. However, to help give you an idea, here is an outline of the different types you can choose from and some popular generator models for each option: Option 1: a portable inverter generator. These are petrol powered, lightweight, quiet, and suitable to run sensitive electronic equipment. You would just run a power board from the outlet of the generator and then plug your appliances in via extension chords. Popular models for your type of application are: Cromtech 2400w Inverter Generator Yamaha EF2800I Inverter Generator More options in this range here: https://www.mygenerator.com.au/inverter-generators.html Option 2: Have an electrician fit a manual transfer switch to your home; this will allow you to switch the power source to your home from mains power or to generator power. So, when a mains power blackout occurs, you can switch over to the generator source, plug the generator in and run either your whole home or certain parts of your home the electrician has isolated. Some people use generator models such as the ones listed above in Option 1, but more commonly, people opt for larger generator models with AVR (Automatic Voltage Regulation), such as: Yamaha Petrol 6kVA AVR EF7200E Generator Pramac Petrol Honda ES8000 7.2kVA Generator More options in this range here: https://www.mygenerator.com.au/avr-generators.html Option 3: An Auto-start generator that will automatically start up and restore power to your home when it detects a mains power failure. These units require a compatible accessory called an AMF (Automatic Mains Failure Panel) and an electrician to install to your main power switch board. Popular models include: Pramac Diesel 6kVA Auto Start Super Silenced Generator Pramac Diesel 8.8kVA Silenced Auto Start Generator More options in this range here (included gas powered gensets): https://www.mygenerator.com.au/auto-start-generators.html Overall, the more common approaches are Options 1 & 2 as they are cheaper and more straightforward. Option 3 has the benefit of automatically reinstating power to your home when a blackout occurs (even when you are not at home), but you'll pay a bit more for this convenience. If you require further help, feel free to call us on 1300 400 122, thanks.

10 February 2017
How about a discussion and or recommendation for a generator for grey nomads where - dare I say it - size matters.

My Generator Response
Hi Paul, you are in luck - we have some good articles for those looking at a generator for camping and caravan applications: Best Camping Generators Revealed Selecting a Generator for Your Caravan Many thanks

28 January 2017
Elight Power Home Generators in Pakistan deal in Small Diesel Generators in Pakistan for commercial purposes. These diesel powered generators are perfect for commercial purposes such as schools, hospitals, super markets, banks etc.for more detail visit our website : http://elightpower.com/

8 December 2016
Its really an informative blog and can clear the differences between diesel and petrol generators for new buyers. We are leading suppliers of FPT iveco, Perkins UK and Lombardini generators in Dubai, UAE. https://www.adpower.ae/

8 August 2016
Elight Power diesel commercial generators in Pakistan are for commercial uses which is beneficial to small scale as well as businesses operating on a large scale.

22 April 2016
An electric generator is a device that converts mechanical energy obtained from an external source into electrical energy as the output.It is important to understand that a generator does not actually ‘create’ electrical energy. Instead, it uses the mechanical energy supplied to it to force the movement of electric charges present in the wire of its windings through an external electric circuit. This flow of electric charges constitutes the output electric current supplied by the generator. This mechanism can be understood by considering the generator to be analogous to a water pump, which causes the flow of water but does not actually ‘create’ the water flowing through it.

My Generator Response
To clear confusion, you should understand that generators DO generate power (EMF), otherwise it would be simply called a motor, or engine. It generates power by mechanically moving a winding through a magnetic flux field, thus causing EMF to occur in the winding, create a load and current will flow. This principle is like an old fashion bike dynamo, where a magnet spins - interacting with windings to produce sine wave power (AC)

18 February 2016
My issue is a generator for Off Grid Solar back-up. The recommended generator is a Honda EU70is 4 stroke GX390 engine electronic fuel injection system max output 7000 w AC - rate output 5500w Recommeded as the quietest around from $6000 plus What can you recommend in either deisel or petrol that would be as good and pricing of same. The off grid solar is 5 kilowat capacity - house/shed - hobby farm usage

My Generator Response
Hi Ian, we sell quite a few generators for the purpose of off-grid solar back up. In answer to your first question, a comparable alternative to the Honda EU70is is the Yamaha EF6300iSE - this inverter generator has the same rated output as the Honda at 5500 watts and is around 27kg's lighter. Currently priced at $5,400. The other options popular for off-grid solar back up are Auto-Start Generators - these units automatically start and stop to top up your battery system when required. There are Diesel, Petrol and Gas powered auto start gensets and I have listed the respective models below most relevant to your inquiry: Pramac 6kVA Silenced Diesel Generator Powerlite Honda 8kVA Auto Start Petrol Generator Generac 8kva Gas Stand By Generator Hope that helps - cheers, Steve

16 October 2015
I have a large industrial diesel generator at my farm and run a small petrol version at my house. I couldn't agree with you more the only thing i would like to add is i find that the diesel generator creates a lot more noise then the petrol version.

My Generator Response
Thanks Markus. Yes, some Diesel sets can be louder than petrol counterparts although it obviously all depends on size of course; generally speaking, smaller gensets will be quieter than larger ones on a like for like basis. However, many diesel generators designed for backup purposes now have soundproof canopies with sound absorbing technology to "silence" the generator during operation. Thanks!

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