Are you saying that kerosene is not evaporating at all prior to the combustion chamber? It is hard to start an engine cold on etherless fuel. I think this indicates that atomization of the carb is not the only factor in burning the kerosene. In the four stroke engines it is quite obvious that the intake tube is operating at maybe 30-40F below ambient while running glow fuel, and while on diesel above ambient temperatures, but somewhat less than the head it is mounted to. D-star has a curious looking carb, I think I read they are doing something special to atomize fuel in the carb.

If the viscosity of the oil mix is only 25% of the original castor oil, how do we know that this isn't actually enough? Many people say that model engine are substantially over lubricated. http://www.klotzlube.com/tech/KL-198.pdf this is a model oriented synthetic lubricant that is SAE 5 rated for model engines at the percentages we use.
http://www.klotzlube.com/tech/BC-175-1.pdf This SAE 50 castor oil product the same comapny sells is recommended for model glow engines at 3-5%!! Nobody I know does this, but they are well known in the lube industry, and I don't think they made a mistake. Why wouldn't 20% even if it's diluted, be suitable to prevent failure?

Ugo, do you have experience with model engines failing with this sort of fuel mix? If so I'd like to hear what happened so I can look for similar problems.

Oil thirsty, compared to what, and how do you define it?