I bought some old small combustion engine for model cars/boats/airplanes. They are not operated using nitro fuel and flow plugs but simply by the (adjustable) compression of the fuel which is why they are typically called „diesel“ engines even though they don’t share that much with their bigger brothers.
I could not get any premixed fuel in my country so I am currently trying to mix my own. Traditionally the fuel is a mix of kerosene, ether, some lubricating oil and a helper like isopropyl- or amyl nitrate. I have been reading some tutorials and experiences from others and it has been mentioned that the kerosene can be replaced 1:1 by regular petroleum without any issues. Also hardly anyone uses the additives mentioned before, so just petroleum, ether and lubricant.
Now to my question. All the homemade fuels I have seen are using castor oil. The same is true for many home made nitro fuels. Naturally I was assuming that castor oil is just the ideal choice, however I saw on Wikipedia that it has the disadvantage of building up gummy deposits and therefore is typically only used for engines that are frequently rebuilt (I.e cleaned). While I don’t mind that I still would prefer not to have this disadvantage. My nitro fuel that is premixed does not use castor oil but synthetic oil, but does not indicate what kind. I am now wondering, is there anything wrong with using regular 2 stroke motor oil like I would use in a motorcycle also for those small (2.5cc) engines? I don’t intend to run them in freezing cold or extremely hot conditions. Or is there a specific reason castor oil seems to be used ubiquitous in home made model engine fuel except maybe cost and availability?
