Thanks, guys. Main problem is that I don't have a really "local" source of anything, fuel or otherwise. I CAN, however add castor to fuel that I have. Or mix and match. That is why I referenced the Cooper, it is 20% nitro. Everything lse is not over 10%, basically.
I was thinking that the Cox needed castor from some long forgotten bit of memory......
I finally got me a Davis "rod setter" for the Cox engines and took a couple apart to check them. All of them had rods that were getting loose in the pistons!
Bill <><