While this is true-about ether being required for the castor and kerosene to mix, diesels DON'T require castor per se-we choose to use it-but mineral oil or synthetics will work quite satisfactorily. If you took the time to check any British modelling magazine of the 50's and early 60's you would find nearly every fuel brand used in diesels available in both castor and mineral oil blends, (often with several different mixes in each) with the castor based ones being considered the premium blends-and more expensive. Even in the 80s and 90s I ran diesels quite satisfactorily using Castrol 2-stroke oil as the lubricant-and for certain uses, most notably FF scale, is desirable, as castor exhaust residue has a deleterious effect on the finish that mineral oil doesn't.

ChrisM
'ffkiwi'