Just about all racing engines used to use castor oil in the sump until the early 1950s, because prior to the various additives being included, mineral oils were just not as good. That is where Castrol took its name from, of course - they named themselves after the best oil available (except for whale oil, which was even better, but extremely expensive). There were problems with castor oil though. The worst of them was that when it got very hot then cooled down, it coated the main and big end bearings with varnish. The varnish then melted the next time the oil got very hot. It didn't all melt at once though, and sometimes the result was a broken connecting rod. (The problem was minor if the engine was run on pure methanol fuel, but because vegetable oil is chemically incompatible with petrol, using the two together was very risky.)
Using vegetable oils such as cooking oil in modern engines is destructive - they can be excellent lubricants, but a chemical nightmare in petrol engines. Because the oil and fuel are incompatible, I would not expect them to mix well so in a 2 stroke mix, lubrication might be quite patchy, as well as the varnish formation problem in hot spots. It doesn't matter much with cheap engines whether they get ruined or not, but putting it in an engine that is worth keeping is just dumb.
