B20 Biodiesel vs Diesel: Vehicle Compatibility
The short answer
Many modern diesel vehicles can run on B20, but only if the manufacturer approves it for your specific engine, model year and market. That approval appears in the owner's manual or warranty documentation, and some diesels are approved only for lower blends such as B5. B20 is never suitable for gasoline vehicles. If you searched for "renewable biodiesel," note that renewable diesel and biodiesel are two different fuels with different compatibility rules.
What B20 is
B20 is a blend of 20 percent biodiesel and 80 percent conventional petroleum diesel. Biodiesel is made from vegetable oils, animal fats or recycled cooking grease through a chemical process called transesterification, which produces fatty acid methyl esters (FAME). Biodiesel is chemically different from petroleum diesel, so the blend level matters for compatibility.
In the US, pure biodiesel used for blending is covered by the ASTM D6751 specification. Blends from B6 to B20 are covered by ASTM D7467. Conventional diesel is covered by ASTM D975, which permits up to 5 percent biodiesel, so fuel sold as ordinary diesel may already contain a small share of biodiesel.
Renewable diesel is not the same as biodiesel
Renewable diesel, sometimes labeled HVO (hydrotreated vegetable oil), can come from similar feedstocks. It is made by a different process, and the result is chemically very close to petroleum diesel. Because it can meet the same D975 specification as conventional diesel, it is generally treated as a drop-in replacement for diesel engines designed for that fuel. Biodiesel is chemically distinct, which is why manufacturers set maximum blend levels for it.
Read the pump label. If it says renewable diesel, B20 limits do not apply in the same way. If it says B20 or another biodiesel blend, they do. Some stations sell blends of renewable diesel and biodiesel; in that case the biodiesel percentage determines whether the fuel fits your vehicle's approval.
How to check whether your vehicle is approved for B20
Read the fuel section of the owner's manual and look for the maximum approved biodiesel blend, usually stated as B5 or B20. Check the fuel filler door or cap, where some manufacturers mark approved blends. Review the warranty booklet. Damage caused by fuel outside the manufacturer's specification may not be covered. If the documentation is unclear, or the vehicle is older or modified, ask a dealer service department about your exact model year, engine and market. Approvals can differ between engine generations within the same model line. Buy blends made to the ASTM D7467 standard from established retailers.
Practical differences between B20 and regular diesel
Cold weather: Biodiesel starts to cloud and gel at higher temperatures than petroleum diesel. B20 is less affected than higher blends, but in cold climates it may need a winter-treated blend, additives or a switch to conventional diesel. Cold performance also varies with the feedstock. Fuel filters: Biodiesel acts as a mild solvent and can loosen deposits left in tanks and lines by petroleum diesel. After a first switch to B20, filters may clog sooner than usual, so an early filter check is sensible. Fuel economy: Biodiesel contains somewhat less energy per gallon than petroleum diesel, so B20 can slightly reduce fuel economy. The size of the effect depends on the vehicle and driving conditions. Storage: Biodiesel absorbs moisture more readily and degrades faster in storage than petroleum diesel. Vehicles that sit for long periods are better served by conventional diesel or careful fuel management. Oil dilution: Some modern diesels use extra fuel injection to clean the diesel particulate filter. Biodiesel evaporates less readily than petroleum diesel, so more of it can end up in the engine oil. This is one reason some manufacturers limit approval to B5. Lubricity: Biodiesel improves the lubricity of diesel fuel, which helps protect fuel pumps and injectors. Seals and hoses: Some older vehicles use rubber fuel-system parts that can degrade with biodiesel exposure. The risk is greatest at higher blends, but owners of older diesels should have the fuel system checked before using any biodiesel blend. Emissions: Compared with petroleum diesel, B20 generally reduces tailpipe particulate matter, hydrocarbons and carbon monoxide. Effects on nitrogen oxides are mixed. Lifecycle greenhouse gas benefits come mainly from the renewable feedstock.
Choosing by situation
Modern diesel with manufacturer B20 approval, used regularly in a mild or warm climate: B20 is a reasonable option if it is available locally. Diesel approved only up to B5: Use conventional diesel or, if the manual permits it, renewable diesel. Avoid B20. Cold-climate winter driving: Use conventional or winter-blended diesel, or confirm that the local B20 is treated for cold weather. Vehicles stored for long periods: Conventional diesel needs less management. Older or classic diesels: Have the fuel system inspected before trying any biodiesel blend. Gasoline, gasoline-hybrid or electric vehicles: B20 does not apply. Never put biodiesel or diesel in a gasoline tank.
What this guide does not cover
Model-by-model approvals, local prices, regional availability and measured fuel-economy differences were not available for this guide, and all of them vary by model year, engine, region and supplier. For a definitive answer about your vehicle, rely on the manufacturer's documentation and your dealer.
