Red means that the Rotopax doesn't carry enough gasoline, to matter in the slightest.
Yellow means that the Rotopax doesn't carry even close to enough diesel fuel, to make the slightest difference.
Blue means that the Rotopax is perfect for starting campfires with Kerosene
Green means that the Rotopax is mounted on a Powerwagon that has a failling cam, lifters, rings, and is drinking oil (again).
Black means ''Who the #$%& did a number 2 in my Rotopax''.
White means that the Rotopax is empty, it's water contents have been wasted by your wife.
Blue Rotopax (is Rotopax plural for Rotopax's?) is the best Rotopax. California agrees.