LPG, Diesel, Petrol.
Which one is best for you?
In researching whether LPG, Diesel or Petrol is the best fuel type for your trip, you may find that the advice is a blanket "diesel is the only way to go".
Although there are many instances when this is true, just accepting this weight of opinion could prove costly, and an unnecessary waste of time.
These three main fuel types in Australia, (and their respective variants) all have solid advantages and reasons for their use, but be aware that all have limitations and drawbacks, especially when it comes to travelling.
So before you buy your vehicle or if you are considering upgrading your petrol 4WD to a Turbo-Diesel, consider the following:
For serious 4WD enthusiasts and people touring outback Australia diesel is by far the most popular choice.
- The most widely available fuel type with even the most remote of service stations stocking it.(and mines if you get into trouble)
- Superior for deep water crossings (with a snorkel fitted) as it doesn't have the electrics of a petrol engine.
- Better for
Towing a Caravan
due to superior low down torque and greater engine breaking due to a higher compression ratio. This is very handy when towing larger vans, particularly in hilly country.
- The least volatile of the fuel types to store and transport, such as in jerry cans.
- Will use around 20% less fuel than a petrol engine of the same capacity for a given tank of fuel. Basically,
you will travel further on a litre of diesel then you will on a litre of petrol, all things being equal. This is handy on very
remote trips as it increases your range and means you can carry less fuel and therefore less weight.
- The price for a litre of diesel varies less between city and rural areas (around 22%) than does Unleaded (around 35%) or Autogas (up to 150%). see
www.fuelwatch.wa.gov.au for recent examples.
- More expensive to purchase a Turbo-diesel vehicle such as a 4WD- typically up to $10,000 more than its petrol equivalent.
- Turbo-Diesels generally require more frequent servicing, depending on usage patterns. This is not so much of an issue with more modern vehicles (last 3-5 years) whose servicing schedules are similar to other engines.
- More expensive. So often over recent years diesel has been around 30% to 50% more expensive than unleaded, and around 50% more than LPG in rural areas and up to 140% more than LPG in cities and larger towns. Even allowing for the fact that a Turbo-diesel is more economical, it is generally a more expensive proposition all up.
- Less tolerant of even a small amount of water getting in the engine than are petrol engines, due to the higher compression ratio. This scenario applies more to extreme 4WD work where very deep water crossings are encountered. Having a snorkel fitted and ensuring the engine is not stalled in deep water (water can run back through the exhaust and into the engine via an open exhaust valve) are two easy ways to eliminate any problems.
TIP: Recent advances have seen the launch of a diesel / LPG system. Rather than being a stand alone system, it is an add on, where the gas is taken in through the air intake and combined with the diesel. With the LPG having a higher octane rating, the system helps the diesel burn more efficiently, creating a cleaner burn and producing up to 25% more power. Should the vehicle run out of LPG, the system reverts to straight diesel. Installation costs are near to $4,500 (plus a $500 exhaust modification required on most 4WD's) with government rebates applicable- see Autogas section below for more details.
- Not availabale in some very remote outback areas.
- More volatile than diesel. Although safe to carry in jerry cans, its fumes can create a potentially explosive atmosphere.
- Some remote communities will not allow unleaded fuel to be brought in except in a vehicle's fuel tank,
which means no jerry cans carrying unleaded.
- Less efficient than a diesel engine. Petrol engines will generally use up to 20% more fuel than a diesel, all things being equal, which will mean on some remote trips more litres will need to be carried.
Premium Unleaded (PULP)
- Due to it's higher octane rating, PULP will generally take you further than regular unleaded, which means you can travel further on a given tank. Anecdotally, 5-10% efficiency can be expected due its higher octane rating. This is worth remembering
if travelling a remote track in a petrol vehicle as it will increase the vehicles range and fuel safety margin. It is however slightly more expensive than regular unleaded and the newer blends like E10 etc.
- Premium unleaded is not widely available outside the major cities and towns, which is an issue for some newer vehicles where the manufacturers recommend only its use.
Even some larger regional towns do not stock Premium unleaded. An example of this is Tom Price in WA, which used its PULP
storage tanks to hold additional diesel for the mines in the area during 2008.
LPG or liquefied petroleum gas (a mixture of propane and butane) is a real and viable fuel alternative for many Australian cars. Autogas, as it is commonly called, has been in use for many decades, having gained its original foothold in the marketplace with the Taxi industry and then steadily gaining wider acceptance, to the point where there are currently around 3500 Autogas outlets in Australia. Some cars such a later model Commodores and Falcons have the LPG conversion factory fitted and engines specifically designed for gas, but the majority of conversions are after market. Consumers have the option of an LPG only system or a dual petrol/gas system.
- The price of gas is much cheaper. Typically in city areas, LPG is around 1/2 the cost of unleaded and normally even better against diesel. This can amount to very large savings. As explained below, this advantage is somewhat diminished in remote towns.
- Autogas has been shown to provide environmental benefits when compared to both unleaded and diesel. Gas provides a reduction in greenhouse gases of around 15% to 20% and produces 20% less smog-forming emissions.
- A supermarket fuel docket offering an 8c/ litre discount is actually double the saving for LPG than it is for petrol and diesel on a % basis Eg. 8c/l off 50c/l for gas is a 16% discount whereas 8c/l off a petrol price of $1.00 is an 8% discount. This further increases the already large cost savings associated with using LPG.
- Can be combined with a petrol engine as a dual fuel system to capture the advantages of both and counter most of each systems disadvantages. Can also be added to a diesel engine to improve the efficiency of that engine.
- Gas conversions are not available on all models and are better suited to some models than others.
- Depending on the type of body, gas cylinders can encroach on boot space, sometimes taking the place of the spare tyre. 4WD
vehicles that have main and sub fuel tanks factory fitted have the advantage of having the gas tank installed in the position
of the main tank and not lose any cabin/ boot space. The sub tank, usually around 60 litre capacity, is then used to supply
the petrol to the dual system.
- Less efficient than either petrol or diesel, using around 20-30% more, all things being equal. This is not a major issue in most circumstances, but can present a problem if travelling long distances in remote areas or having a gas only system, which is generally too limiting to realistically consider. The primary reason for not choosing a gas only system is that is you run out, you must be towed back to a service station, as you can't carry gas in a jerry can!
- LPG is widely available in most parts of the country, but this is not always the case in rural and remote areas. You will need to plan longer trips with this in mind. However, dual fuel vehicles have the added capacity of both tanks which increases the range of the vehicle and makes this less of a problem.
A word of caution here- in the less populated areas, do not rely on the indicated service station actually having gas. Most
often this is a result of the bowser being out of service and the service station waiting months for a repair person to come
and fix it. This happens with annoying regularity in some areas and given that each station has only one bowser, it can leave
you stranded unless you have a dual fuel system.
- Cylinders must be inspected and tested after 10 years in some states.
- Not recommended for all cars. Gas engines run "drier" than petrol which can cause engine problems such as valve
recession, which can offset any fuel savings. There are measures that can be taken to help prevent this, such as running the
engine regularly on unleaded if the vehicle is duel fuel (up to 10% of the time is recommended by some mechanics) and the
installation of an inexpensive Flashlube Valve Saver. That said, I have run my current Prado on LPG for over 10 years, have not even used a valve saver additive or the like and the vehicle is still running brilliantly (and approaching 300,000km).
- Installation costs must be factored in. Typically, an after market install is around $2,500.
A new part of the LPG story
The story of LPG is a constantly changing one. Unfortunately, the advantages of having an LPG conversion done to your vehicle have diminished significantly in recent times. Increasing government taxes have increased the prices, but with more Australians demanding the government fix any societal ill, we can expect more taxes on lots of things as that money has to come from somewhere.
Incidents like the Cootes tanker tragedy and the subsequent grounding of their fleet resulted in widespread shortages and big price hikes that would have caused outrage if the same hikes had happened to unleaded or diesel. From my observation, the prices did not recede much once normal supplies resumed.
The final thing that I am aware of that has lead to a trajectory of high LPG prices is the large gas plants being built in places like Gladstone in Queensland. Apparently, to help the overall viability of these projects, the government has pegged the national LPG price to the world market, which is another nail in the coffin for LPG. Please feel free to drop me a line if anything I have listed here needs correcting.
In October 2013 I was in Cape Range National Park in WA. At night from our camp I could see the glow from the gas rigs off the coast, and yet the LPG price in Exmouth and most of WA was $1.45, $1.31 on the outskirts of Perth. Surely they are kidding!
Fortunately the large drops in the world price of oil in 2014 and 2015 have given us all some respite- enjoy it while is lasts!!
With so many pros and cons for each of the three fuel types it is important to be clear on exactly what your needs are before
A Turbo-Diesel is the most practical if you are planning to get serious with your 4WDriving or you want to traverse into the really remote desert regions of Australia, such as the Canning Stock Route. It is also recommended for towing of heavy caravans. But you will pay for the benefits, and pay substantially more, both in the purchase of the vehicle and in fuel costs. This extra money only makes economic sense if the need is really
If your trip is anything less than that above, then all the options are yours to choose from. A petrol/gas dual fuel system in a 4WD where both tanks are under the vehicle is a very good and versatile option. It offers very substantial savings over a
diesel and will still take you almost anywhere in this great land.
In a petrol/gas Prado, we recently tripped around Australia with two other families who had diesel Prados with all of us towing 2 tonne off-road-caravans. Travelling to the usual blacktop destinations and then tackling tracks like all of the Gibb River Road, Oodnadatta Track, Painted Desert and Cape Leveque and more, we found that our fuel costs were lower, particularly in the more settled areas of Australia. In the remote areas, gas was either too expensive or not available, which meant we were buying petrol and paying almost as much as the diesels. The only drawback we had was having to stop more frequently to fill up (not really an issue as it helps with driver fatigue) and having to be pulled out of the Ord River at the Ivanhoe Crossing by a diesel. This was the only incident in dozens of river crossings.
All up a very small inconvenience for having saved almost $10,000 on the purchase price and further savings on the fuel.
Our petrol gas Prado is also a lot cheaper to run when at home running around larger towns and cities where the price of LPG is at its most competitive.
If you are considering swapping your petrol 4WD to a diesel, whilst considering the above, don't forget to take into account
stamp duty and other costs and time associated with the purchasing a new vehicle.
See Our Fuel Costs as we Travel Australia
MONEY SAVING TIP: A great way to save money on longer trips is to avoid filling at roadhouses wherever possible. This may mean carrying fuel in jerry cans, or just ensuring that both main and sub fuel tanks are full. We have always found it worth the effort.
Roadhouses are much more expensive than the service stations in the nearest towns. Nanuturra Roadhouse (Pilbara), Timber Creek (NT.) and the stretch across the Nullarbor and the Barkley Highway are some of the worst areas we have seen for these puzzling price extremes.
See Our Fuel Costs as we Travel Australia
Great money saving tips for you to Travel Australia
Return to HOME PAGE from Diesel Petrol LPG