A Q U I C K CO U R S E O N B I O D I E S E L B L E N D E D F U E L S .- Page 3

Biodiesel is diesel fuel made from vegetable oil or animal fat which is processed with methanal to be used as a bio 
substitute for conventional diesel fuel. Some states offer certain incentives to blend biodiesel into highway diesel fuel. 
The percentages of biodiesel in highway fuel can vary, as can the quality of the ingredients and process used to make it. 
Fuel that is not up to the right quality standard can damage your engine and fuel system.

Your Mazda will operate most efficiently on diesel fuel with the specification ultra-low sulfer diesel (ulsd, 15 ppm 
or less) fuel that meets the ASTM D975 standard or equivalent. Fortunately, it’s easy to determine if fuel is right for 
your Mazda by looking at the label on the fuel dispenser. Always verify the fuel grade before refilling. 
If the fuel grade cannot be verified, ask the gas station attendant for assistance.

A   Q U I C K   CO U R S E   O N   B I O D I E S E L   B L E N D E D   F U E L S .

B5 AND BELOW IS APPROVED

Diesel fuel with biodiesel con-

tent of up to 5% will generally be 

labeled “ultra low sulfer diesel”  

or usld. This is approved for use  

in your new Mazda. Fill up with 

this fuel from a name brand fuel 

station whenever possible.

B6-B20 IS LIMITED USE

B-20 biodiesel blend contains 

biodiesel content between 6%  

and 20%. The use of this fuel is 

generally not approved by  

Mazda and should be used only  

on a limited basis and only if  

unavoidable. Always make sure  

to buy this fuel from a name  

brand station whenever possible.

B21 AND ABOVE IS PROHIBITED

Never use fuels containing more than 20% or higher 

biodiesel. If B-20 is used, do not let the fuel remain in 

the vehicle for an extended period of time. This may 

cause severe damage to your engine and fuel system 

which will not be covered by your Mazda new vehicle 

limited warranty.

If you must use B-20 fuel on a regular basis monitor your engine oil level closely, strictly follow the oil change intervals quoted in 
the instrument cluster and in your owner’s manual, and use only engine oils and filters approved by Mazda for use in your vehicle. 
Limit engine idling time to less than 5 minutes.

Biodiesel is produced from raw vegetable oil or animal fat, and it’s chemically different from petroleum based diesel. 
It poses quality risks that depend on feedstock, as well as the production process. Due to these shortcomings, it’s 
possible for harmful by-products like metals or free fatty acids to contaminate biodiesel. Use of biodiesel from 
non-name brand distributors or retailers increases the possible negative effects. 

U S E   T H E   R I G H T   F U E L   TO   AV O I D   T H E S E   P O T E N T I A L   P R O B L E M S :

-Clogging of fuel filter caused by soaps that may contaminate biodiesel blends. 
-Clogging of fuel filter due to the growth of microbes in free water contained in biodiesel blends.
-Fuel gelling under cold climate conditions.
-Sludge formation in engine oil.
-Deposit formation on piston rings, oxygen sensors and exhaust gas recirculation parts.
-Nozzle coking and injector deposits.
-Engine oil dilution because biodiesel is not evaporating from engine oil when fuel enters the engine during particulate   
  trap regeneration. This is especially true when driving under low load and low engine temperature conditions.

“ W H AT   CO U L D   G O   W R O N G   I F   I   U S E   T H E   W R O N G   F U E L ? ”

ACCEPTABLE GRADES FOR USE ARE: DIESEL NO. 2 AND B-5 DIESEL.