Stormin Mormon wrote:
Yellow is for diesel fuel.

Of course, ideally, the proper color container for the
proper fuel. As you said, it's wise to label the container
if used in emergency for some other fuel.

A trace of kerosene won't hurt gasoline, if kerosene must be
hauled in a red container.

I've heard more than one person say they mixed gasoline & kerosene 50-50
back during WWII when there was gasoline rationing. Smoked a bit but no
damage. In todays cars... who knows? I wouldn't want to risk it
killing a bunch of sensors. But like you say, a trace amount won't hurt
anything