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Can You Safely Run Alternative Fuels in Your F-250 Diesel?

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Table of Contents
  1. What is Natural Gas - CNG?
  2. How to Run CNG Safely
  3. Pros and Cons to Running CNG Over Diesel
  4. What is Propane?
  5. How to Run Propane Safely
  6. Pros and Cons to Running Propane Over Diesel
  7. Natural Gas in Comparison to Propane
  8. Other Alt Fuels You Can Run
  9. Regarding Heating Oil and Off-Road Diesel
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Diesel engines are nothing short of miracle machines. They produce unrivaled power, uncanny durability, and can even produce impressive fuel economy numbers despite their massive size in both displacement and mass. What many F-250 owners may not know is diesel engines can even be modified to run alternative fuel. Some of these modifications you may have heard of but others may take you by surprise. Before taking any of these alternative fuels into consideration, we will need to take a look at which fuels you can run safely or legally in an F-250.2011-2016-f250-out-in-the-wilderness.JPG

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What is Natural Gas - CNG?

Running natural gas in a diesel engine is nothing unusual. Studies suggest nearly 12 million vehicles worldwide have been converted to run natural gas. CNG, compressed natural gas, is a combination of mostly methane and hydrocarbons. This substitute costs about half as much as diesel fuel, and produces nearly 90% less emissions. It’s a safer and cheaper fuel than diesel. Despite being a compressed gas, its range of flammability is extremely narrow and it disperses quickly, which makes CNG less likely to ignite in an accident than gasoline.

How to Run CNG Safely

Converting your F-250 in order to run CNG is no quick process. This fuel type does have a very narrow window of being flammable, and in order to run it, your engine will need to produce the right conditions. The modifications needed to run this fuel are low compression pistons, the addition of spark plugs and a timing system in order to ignite those plugs, proper fuel injectors, and gas mixer. Of course there is also the issue of setting up the proper fuel system.

Pros and Cons to Running CNG Over Diesel

With such a complicated procedure required to run natural gas, you may be wondering what the benefits are to running natural gas as opposed to the drawbacks. The biggest benefit that tips the scales in favor of this fuel type is the cost of the fuel. Diesel fuel costs nearly $4 a gallon, while CNG runs around $2 a gallon. Even if you were to get the equal amount of miles to the gallon, you’d be saving tons of money annually.

It’s also worth mentioning that CNG is much better for the environment than diesel fuel. Though, these benefits do come at a cost. Upgrading a diesel engine to run CNG can be costly, and you will lose power. You’ll also need to be aware that a CNG pump will be hard to come across and filling your tank can take significantly longer to do. Though, you can opt to run a bi-fuel system which allows them to switch between either diesel fuel or CNG as needed.


  • Low cost of fuel
  • Good for the environment
  • Bi-fuel systems available


  • Complicated and costly to set up
  • Fuel is hard to find
  • Produces less power

What is Propane?

Propane is another alternative fuel to diesel. This fuel type is commonly known as propane but is also known by the name of liquefied petroleum gas, or LPG for short. It’s produced from crude oil refining or natural gas processing. In terms of an alternative fuel choice, it too is very affordable and safe for the environment which is why many diesel vehicle owners opt to run this as fuel in their engines.

How to Run Propane Safely

To run propane safely, the F-250’s diesel engine will need to be heavily modified. Just like converting the engine to run on natural gas, you will need to run aftermarket pistons in order to lower the compression ratio, you’ll need a timing system, and spark plugs will also need to be installed along with the proper fuel delivery system.

The buck doesn’t stop there though. Diesel engines have a very short RPM range and with diesel fuel, this is acceptable on account of the peak power and torque being produced at low RPMs. Propane will not produce power until a higher RPM, which means the valvetrain will need to be reworked. This, of course, leads to sacrificing durability and longevity of the engine.

Pros and Cons to Running Propane Over Diesel

While propane is certainly a cleaner fuel to run than diesel, the complications associated with running this as an alternative fuel seem to outweigh the pros. For one, even though you can run bi-fuel systems with propane, the entire nature of the engine will be altered and not for the better in comparison to running diesel. It’s also very costly to make these upgrades and the power of the propane is comparable to natural gas. Although the fuel only costs around $2.50 a gallon which makes it worth reading into.


  • Low fuel cost
  • Safe for the environment
  • Can be run in a bi-fuel system


  • Costly and complicated install that completely reworks the engine
  • Produces less power

Natural Gas in Comparison to Propane

In theory, natural gas and propane sound very similar. This may leave many in a coin toss trying to decide which alternative fuel source is better. Both require the engine to be reworked. Both can save F-250s a lot in fuel costs, and both can be less harmful to the environment than diesel fuel.

So which is better? Well, natural gas is half of a dollar cheaper per gallon and more common as an alternative fuel. This means it will be easier to find fuel pumps designed for the vehicle. But natural gas produces less power than propane in an internal combustion engine.

Natural gas general runs a 25-percent power loss when stacked against diesel, while propane only suffers from a 15-percent loss. To truly reap the rewards of this additional power, the engine needs to be dramatically altered. In the long run, natural gas is the clear winner on account of the fuel costing less per gallon, and less work needs to be done to a diesel engine to run it.

Other Alt Fuels You Can Run

While common, LPG and CNG are far from the only alternative fuel to diesel engines. Synthetic diesel, biodiesel, vegetable oil, ethanol diesel blends and even hydrogen have all been used in engines that have been converted to run them. One must remember that alternative fuels may be cheaper or safer to run, being able to purchase them or create them regularly needs to be considered.

Regarding Heating Oil and Off-Road Diesel

How about the cheaper heating oil? Yes, your diesel engine can run on it. The two fuels are nearly identical, and heating oil is much cheaper than diesel fuel. But don’t go running to the local heating oil source to run it in your F-250. Diesel fuel is more expensive for a reason: road tax. If you get caught running a diesel engine on the highway with heating oil in it, Johnny Law is going to fine you so fast your head will spin. Off-road applications are another story – you won’t get any fines there.

Kerosene is also very close to diesel and heating oil, but it is also a no-go for road driven vehicles. An interesting note is Kerosene does not gel up like diesel, but heating oil will. In fact, in extremely cold regions like Alaska, it’s not uncommon to see kerosene being burned in equipment intended to run on diesel when it gets super cold.

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