I'm pretty sure that Jon told us that his rubber supplier said the red ones and black ones are made from the same material. It seems to be an urban legend that the red ones hold up better - sort of like a placebo.
I have had one of his black ones in my carburetor since Feb 2021 and this truck burns ethanol exclusively. No problems whatsoever.
Since his main supplier uses black rubber now, he has to buy the red stuff elsewhere at a higher price and sell it at a premium to the customers who think it's better.
