Choosing The Right Fuel; Octane Recommendations; Unleaded Gasoline Engines - Mazda B4000 Owner's Manual

Maintenance and Specifications
WARNING: The fuel system may be under pressure. If the fuel
filler cap is venting vapor or if you hear a hissing sound, wait
until it stops before completely removing the fuel filler cap.
Otherwise, fuel may spray out and injure you or others.
WARNING: If you do not use the proper fuel filler cap,
excessive pressure or vacuum in the fuel tank may damage the
fuel system or cause the fuel cap to disengage in a collision,
which may result in possible personal injury.

Choosing the right fuel

Use only UNLEADED FUEL. The use of leaded fuel is prohibited by law
and could damage your vehicle.
If your vehicle is a flexible fuel vehicle (FFV), use only UNLEADED
FUEL and (E85) FUEL ETHANOL. The use of leaded fuel is prohibited
by law and could damage your vehicle.
Do not use fuel containing methanol. It can damage critical fuel system
components.
Your vehicle was not designed to use fuel or fuel additives with metallic
compounds, including manganese-based additives.
Repairs to correct the effects of using a fuel for which your vehicle was
not designed may not be covered by your warranty.

Octane recommendations

Do not be concerned if your engine
sometimes knocks lightly. However,
if it knocks heavily under most
driving conditions while you are
using fuel with the recommended
octane rating, see your authorized Mazda dealership to prevent any
engine damage.

Unleaded Gasoline engines

Your vehicle is designed to use "Regular" unleaded gasoline with an
(R+M)/2 octane rating of 87. We do not recommend the use of gasolines
labeled as "Regular" that are sold with octane ratings of 86 or lower in
high altitude areas.
212
87
(R+M)/2 METHOD