What kind of paint would be good for labeling cans for gasoline, diesel, and kerosene, using stencils? Or, maybe it shouldn’t be paint?
It’s important that it work neatly with stencils and that it resist being dissolved by fuel spills. The cans are painted steel
I was figuring on using a good brand of spray paint, like Rustoleum. Is there anything better for this?
In the USA it’s customary that cans for the fuels you mention be painted the following colors:
Gasoline-RED
Kerosene-BLUE
Diesel Fuel-YELLOW
So no labels are needed. 
The plastic cans sold for the purpose are molded in the appropriate colors.
You’d want some type of enamel paint I’d say.
FYI, Harbor Freight sells stencils.
Personally, I’d clean the surface well, scuff with 320 grit and then brush on Rustoleum.