As environmental concerns and fuel regulations evolve globally, Yanmar equipment owners increasingly face decisions about which fuel type best suits their respective operations. This article examines three primary options—conventional diesel, biodiesel (FAME), and Hydrotreated Vegetable Oil (HVO)—explaining what they are, each type’s respective compatibility with Yanmar engines, and important considerations for effective operation and proper maintenance.
Conventional Diesel: The Baseline
Conventional diesel fuel—derived from petroleum—has been the standard for diesel engines for more than a century. For Yanmar industrial engines, it provides maximum engine performance and power output. It is also widely available via established infrastructure and with consistent quality standards across the globe, with some variations. More importantly, no special engine modifications are required.
As energy preferences and regulatory landscapes continue to evolve, however, some equipment owners are exploring alternative fuels to align with operational goals, sustainability initiatives, or regional requirements. While conventional diesel remains a reliable solution, newer fuel options—such as biodiesel and HVO—offer unique benefits and trade-offs. Understanding the operational impact, maintenance implications, and compatibility of each fuel type is essential when evaluating which option best supports long-term engine performance and efficiency.
Biodiesel (FAME): Partial Renewable Solution
A major alternative is biodiesel, specifically Fatty Acid Methyl Ester (FAME), produced from biological oils such as soybean, rapeseed, palm oil, or animal fats through an ester exchange process. Biodiesel is typically mixed with conventional diesel and labeled according to its concentration (e.g., B7 contains 7% FAME and 93% diesel, while B20 contains 20% FAME and 80% diesel, etc.).
As a partially renewable resource, biodiesel helps reduce dependency on fossil fuels. Furthermore, it reduces particulate matter (PM), carbon monoxide (CO), and hydrocarbons (HC) in exhaust. It also has a higher flashpoint than conventional diesel, making it safer to handle.
However, biodiesel can accelerate oxidation of certain metals (aluminum, brass, bronze, copper, zinc), compared to diesel, eroding engine parts faster. Parts that include certain rubbers and resins in seals, gaskets, and hoses can also degrade faster over time. Thus, the use of biodiesel often requires more frequent maintenance intervals at higher concentrations and the use of alternative types of engine parts and materials that may not come standard, resulting in the need to procure specialized replacement components and parts.
Furthermore, the higher the concentration of FAME, engine output can be slightly reduced by approximately 2% with B20 along with increased fuel consumption of approximately 3%. It also increases toxic nitric oxide emissions while limiting the storage life, making it difficult to use if equipment is not operated for months at a time.
HVO (Hydrotreated Vegetable Oil): The Drop-In Alternative
HVO falls within a broader category of renewable diesel fuels. HVO is typically produced from vegetable oils through a different process than biodiesel.
To start, they are a 100% renewable fuel source and can be used as a “drop-in” replacement for conventional diesel without special modifications or parts replacements. This means there is no change in required maintenance intervals, and it can be mixed freely with conventional diesel with no issues. In comparison to biodiesel, it also maintains better storage stability.
The main downside is that it is of lower density compared to conventional diesel, potentially resulting in reduced engine output and higher fuel consumption rate. It is also not as widely available as conventional or biodiesel, and it’s often more expensive to purchase.
Guidelines for Alternative Fuels
For safe operation of Yanmar engines, depending on the particular fuel source, we offer a set of guidelines and recommendations to make the most of each Yanmar industrial diesel engine given the chosen fuel type. The idea is to preserve the integrity of the engine by providing proper maintenance at the correct intervals for the primary fuel utilized.
For Biodiesel:
- For varieties B7 and below, there is no special preparation required. Standard maintenance applies.
- For B8 to B10: No parts replacement needed, but maintenance intervals for fuel filters, water separators, and tank draining should generally be cut in half compared to conventional diesel guidelines.
- For B11 to B20/B35 (depending on engine group): Specific parts replacements may be required, particularly for fuel system components exposed to the fuel. Yanmar offers a factory-supplied update kit for select engines, which includes filters and fuel system parts made with B20-compatible materials. Operators should also confirm that the entire machine—not just the engine—is designed for B20 compatibility, as non-Yanmar components like hoses and separators may require OEM-specific upgrades.
- Finally, always use fuel that meets established standards such as EN14214 or ASTM D-6751, to name a couple.
For HVO and Other Renewable Diesels:
- Keep in mind that utilizing HVO is just like using conventional diesel, in that there are no special parts, maintenance changes, or maintenance interval timeline adjustments required.
- However, operators should be aware of potential performance reductions.
- Finally, operators should ensure fuels comply with applicable standards, such as EN15940.
What’s the Right Choice?
The right fuel choice for the Yanmar engine depends on many factors, ranging from the design of the given engine itself, its intended usage, and even the price of fuel an operator is willing to spend. In some cases, operators may also consider broader priorities, such as compliance with local environmental regulations, corporate sustainability goals, or alignment with industry trends. Each of these considerations plays a role in determining the most suitable fuel type for long-term engine performance and operational success.
To start, consider the following questions when determining the best fuel type:
- Application needs – Is maximum power critical, or is environmental impact more important?
- Maintenance capacity – Can one adhere to more frequent service intervals if using higher biodiesel blends?
- Regional availability – What fuel options are readily accessible in a given location? Will the engine be taken to other countries or regions? If so, what fuel options are available there?
- Fuel cost – How much does the fuel typically cost in comparison to alternatives?
- Regulatory requirements – Are there local mandates, laws, or regulations affecting fuel choices?
- Expected usage – How often will the operator run the engine? Will it be daily or weekly? Will the engine be put in storage for months at a time?
- Age of equipment – How old is the engine? Older equipment may require updates to use higher biodiesel blends safely.
Lastly, it’s important to remember that using fuels not recommended by Yanmar can impact engine performance, reduce longevity, and may void warranty coverage. Specifically, any damage resulting from “the use of fuels, oils, lubricants, or fluids other than those recommended in your Yanmar Operation Manual” may not be covered under the Yanmar Limited Warranty for Industrial Engines and Generators.
For detailed warranty information, visit the Yanmar Industrial Engine support page. To ensure compatibility with alternative fuel sources, always consult your engine’s operation manual and speak with an authorized Yanmar distributor or dealer. Taking these steps is essential before making any changes to the fuel type used in your engine.
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