I tried a bottle of Lucas once. Didn't notice any difference, but I kept the bottle. Oz. markings on the side make for easy measuring for any fill up. I screwed a leftover piece of 4" exhaust pipe to the inside of my bed just behind the toolbox. I cut the top and bottom off on one side. The top, that's where I put the mounting screw. The bottom I folded over to make an actual bottom for the holder. Lucas bottle full of PS fits in there quite nicely and never spills or tips over. It's completely out of the way for putting stuff in the box. If my description doesn't make any sense, PM me and I'll email ya a pic.