Well, I've run a number of no ether mixes using mineral oil and also Klotz castor. This is a highly refined and perhaps modified castor oil. It does work. I have tried other Castors such as Sig and the drug store variety and they don't stay mixed, as you say, without at least some ether. But again, the temperatures have to be reasonable for Klotz to remain suspended.

But I'd be happy to send you some Klotz if it's hard to get on that beautiful Island of yours. Send me a PM. Engine testing season is here !!

I like your idea of a blend of the three oils. There DOES seem to be some kind of undiscovered magic with Olive oil. Hopefully, I can get to testing some of those blends soon.