Taken from the B205 FM
Here in Northen Canada we operate Jet A1 fuel with FSII all year around, they don't even bother changing in the summer.
JD
ANTI-ICING FUEL ADDITIVE
When operating in temperatures below +40°F (+4°C), all fuel used in this helicopter
shall contain an anti-icing additive meeting the specification requirements of
PFA-55MB. Concentration of this additive in fuel in a loaded fuel tank shall not be less
than 0.035% nor more than 0.15% by volume. The minimum concentration of the
additive in the fuel with which the helicopter is to be refueled should be a least 0.06% by
volume to assure a loaded fuel tank concentration of at least 0.035%.