GHB,
I agree about the castor oil being better than the mineral oil, but its not bad either (look at indy cars and NASCAR some still use it) the main reason it is not used in glow fuel is it doesn't mix with methanol. That aside for this discussion the reason for the mineral oil is to calm the ether. If you read the section for Fixed Compression diesel on the web site you posted you will see Adrian supports this (he also supports that kero is the power ingredient in modern diesel). With the simple diesel fuel proposed the power ingredient is the heptane (as it comes from the SF can) in place of the kero. Heptane doesn't calm the ether as much as the kero would so using mineral oil will do that. I think the reason kero became the main component was cost, its very inexpensive compared to ether, also very available. I'm not saying that the simple diesel mix is the best, just that it would work for most sport flying and could be easily obtained without the expensive shipping costs of commercial blends.

Best, DennisT