ACF50 Aviation MIL-SPEC81309
Used for a few years now .No rust problems and the oil additive they sell does exactly what it says on the bottle.
I had a spare motor cycle engine in long term storage about 15 years with there oil additive not AC50 in and its restarted no problems as to whether it was the additive or just good luck who knows but for what it costs I lay my bikes up with this additive and have not had any problems with rusting or condensation
That's my 2p for what its worth