He only did the rv because he doesn’t have diesel powered lawn mowers! Haha. Seen a lot of his videos. But ya that had room for error, but the main point is it doesn’t help more than gasoline and basically what it is made of.
One of the things he didn’t cover was water in the fuel and the related effects.
The lubricity of the products COULD change by how it acts when mixed with diesel, yes. But really, mix in 50/50 diesel and water, 50/50 diesel and engine oil. Then straight water and straight oil. Pretty easy to see what would happen.
In all the lube tests I was involved in in an actual lab, one thing was consistent- better stand alone lubes did better when cut into fuel every time I ever saw. The one in a million chance that one of those brands has the perfect chemical agent to break the rule, I would push all in against it happening.