Mike has an RC car with a 3.3cc engine (yep, I just finished reading your post in the RC car section). Methylated spirits would be your best bet to try because it's usually 95% ethanol (drinking alcohol) with the rest usually methanol to make it undrinkable and then it can be sold as a cleaning fluid
. Ethanol won't give as much power as methanol but who cares if you're just bashing around
. The only possible problem is keeping the glow plug hot. Normally it glows all the time because it reacts with methanol and, although a lot of guys say it works well with ethanol, I've never tried it myself. I believe you've got some Castrol M castor and that's ideal so mix it at a 4:1 ratio (20%) with the metho. You can't use auto type synthetic oils because they won't mix with alcohols.
Model diesel fuels are what was used in some glow engines and that's entirely different to the diesel fuels used in cars or trucks. Avgas is just a type of petrol and that won't work in glow engines either. As far as compression goes without nitro, don't worry about it because all engines run quite well without nitro. They just don't make quite as much power, mainly because compressions are optimised for nitro. You could take out the head shims but that doesn't give a worthwhile increase in compression so just leave it as is.