Blitz cans
#2
I would suggest the plastic formula spray paints. I've used them on a lot of different plastics and they seem to hold up pretty well. The problem with gas cans is you're always spilling gas on them so the paint is sure to loosen up pretty quick, but hey, it's a gas can. The only real worry is technically a gas can has to be red but I really doubt you'll ever catch any flak for it.
#4
JK Jedi Master
ASTM F852, Standard Specification for Portable Gasoline Containers for Consumer Use:
4 Requirements.
4.1 Color. The container shall be predominately red in color. Pigments, coatings, or other means used to impart color shall not be affected by gasoline.
ASTM F976, Standard Specification for Portable Kerosene and Diesel Containers for Consumer Use:4.1 Color. The container shall be predominately red in color. Pigments, coatings, or other means used to impart color shall not be affected by gasoline.
4 Requirements.
4.2 Color. Kerosene containers shall be predominately medium blue in color. Diesel containers shall be predominantly medium yellow in color. Pigments, coatings, or other means used to impart color shall not be affected by kerosene.
Now, being a voluntary standard does not mean that states and localities haven't passed laws to implement it. But, the American Society for Testing and Materials is an organization that creates and sells (in written form) voluntary standards for industry and governments to implement.4.2 Color. Kerosene containers shall be predominately medium blue in color. Diesel containers shall be predominantly medium yellow in color. Pigments, coatings, or other means used to impart color shall not be affected by kerosene.
I also agree with the assessment that you're unlikely to be stopped for having an incorrectly colored jerry can. However, you may run into gas stations where they'll stop you from filling a gas can that is anything but red.