Ask Dave / Posted 3 years ago / 997 views

Question:  I am trying to figure out if bio fuel is safe for my CAT engine.  There is a lot of conflicting information out there and it’s hard to tell what’s right.

Submitted by John Appleton, Long Beach, CA
Beaver Marquis, Cat C12

Here is the information on biofuel for cat engines straight from Caterpillar.

BioFuel is made from Vegetable oils, animal fat, and waste cooking oil. Soybean oil and rapeseed oil are the primary vegetable oil sources. The raw oils or animal fats are chemically processed ( esterified ) to form a fatty acid methyl ester ( referred to as frame ), the esterified product ( frame ) is biodiesel fuel that can be used in compression ignition engines. Without the chemical processing referred as esterification, the oils or fats are not suitable for use in compression ignition engines. In order to use any of the oils or fats listed above as fuel, the oil or fat must be esterified and the WATER and CONTAMINANTS removed

Here is a summary of Caterpillar recommendations with the latest revision of ( ASTM-D7467 ) specifications for B6-B20 blend biodiesel blend for most engines:

For engine production years C-13 and C-15 certified by the EPA in  2007 and newer models,  you can burn up to B20.  Caterpillar C-7 and C-9  certified  by the EPA in 2007 and newer models  can go up to B15.  The use of diesel fuel cleaner (Part Number 343-6210) at every oil change is recommended by CAT and diesel fuel nozzle cleaner (Part Number 304-7755 ) also to clean the ARD nozzle.  For model years 2006 and older, all models can use up to B20. For all applications running biodiesel or biodiesel blends, it is recommended you use either CAT Diesel Fuel System Cleaner (Part number 343-6211 ) or CAT Diesel Fuel Conditioner (part Number 256-4968 ) in the fuel.The CAT fuel conditioners improve fuel stability.

Oil change intervals can be negatively affected by use of biodiesel. CAT recommends using CAT S-O-S Services Oil Analysis to monitor the condition of engine oil and help determine oil change intervals. Note: CAT fuel filters and CAT fuel water separators are compatible with Biodiesel fuel. Filter biodiesel and biodiesel blends through a fuel filter with rating of 4 microns absolute or less. Biodiesel fuel provides less energy per gallon by 5 percent to 8 percent.


Monitor the condition of seals and hoses regularly. Biodiesel may soften, degrade, or leak from

some types of elastomer used in seals and hoses. CAT engines built in early to mid 90’s use Viton seals and Viton o-rings. Nitrile hoses that are used in some fuel transfer lines are not compatible with biodiesel fuel.

The addition of CAT Diesel Fuel Conditioners, (Part Number 256-4968), or an appropriate commercial additive containing antioxidant/oxidation improves stability and is strongly recommended.

InGen Sets, Diesel Generators, and emergency vehicles using biodiesel fuels, care must be taken to remove water from fuel tanks. Water accelerates microbial contamination. Caterpillar strongly recommends in smaller engines the use of Caterpillar fuel filters and CAT water/fuel filters and Caterpillar Diesel Fuel Conditioner # 256-4968 and Caterpillar Diesel Fuel Cleaner  # 343-6210 or appropriate commercial conditioner and Cleaner.  With the bigger HP cat engines the heat from return fuel will allow Biodiesel fuel to pass through the fuel filter. With the smaller HP Engines the return fuel does not warm enough to pass the thicker Biodiesel fuel through the fuel filters. The use of Diesel fuel fuel conditioner will thin wax or paraffin and allow it to pass through the fuel filter.

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Fuel System

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