RE: DA50 on 100:1 Amsoil would you could you !!!????!!!???
Model engines is a small nich market for manufacturers. They test their engines with products that either are available or seem to be suitable. Once the engine performs well, they recommend the oil they tested with. This does not mean there are no other oils that are suitable.
Synthetic oils are well known for their improved adhesion to metals, as well as the slipperiness of the film. In car engines you may get 10% milage improvement with synthetic oil. That also means more shaft power,
Synthetic oils tend to flash off suddenly when at elevated temperatures, where mineral oil decomposes, and still gives some protection. Vegetable oil like castor keeps on lubricating even beyond the range of mineral oil. If the engine is kept cool, there is no reason to use mineral oil for running in, and then switch to synthetics. Every switch in oil needs the engine to re-adjust, during which period the internal components are at risk due to the unknown oil compatibility issues.
Tests have been run comparing 100:1 oils with 50:1 oils. Regarding wear ratio, the 100:1 oils lost the battle. Regarding overall power output, the only oil I know of at 80:1 ratio in competition is Belray. Maybe someone can enlighten me on 100:1 use in competition.
Our model engines do not 100% compare to competition engines, because we use low rpm applications. That makes the engine run hotter, and thus we tend to supply too much fuel in order to keep the engine from sagging. Doing so supplies more oil as well, which feeds the controversy.