No such thing as a dumb question once asked.
I have not used the aerosol version (and won't because I only want product not product and carrier AND i want to control where it goes)
3-in-1 is NOT ok for sewing machines because it is too thick and dries with heavy residue
Sewing machine oil can go bad. It does not last long enough in my house to do so, but i have been told any product using organic compounds can "rot"
I use Sewing machine old exclusively for cleaning my machines. My collection is all 1901 and earlier machines and I will NOT use chemicals on them if I can possibly avoid it.
I use Tri-Flow liquid exclusively for lubricating my machines. In MY opinion the long term effects of tri-flow will be superior to the long term effects of oil (Oil dries to varnish - not a lubricant, Tri-Flow dries to teflon- still a lubricant)
I buy my Sewing machine oil on 1 quart bottles. I found out about the bulk size when Heather got her 1946 Singer industrial which actually has an oil pan and pump to constantly oil it as it runs. WAYYYYYY cheaper that way.