It's a very long time (45 yrs) since I was one of many owners taking part in the BGA trials of Mogas, in those days Four Star and leaded. We found that four-star made for a cleaner engine, while automotive multigrade oil gave far easier starting in winter and constant oil pressures instead of the sky-high when hot, very low when cold of Aeroshell 80/100. This was proven in countless aerotows mostly with Gipsy Major and Lycoming engines.
Today I'm years out of touch, and maybe today's unleaded motor fuel is not so prone to vapour locking. Our old-fashioned and doubtless dangerous demo was to pour a capful of Avgas on the concrete with a capful of Mogas beside it; the Mogas evaporates in seconds, the Avgas stays damp for much longer. If the fuel pump is attached to the hot crankcase the fuel may vapourise, resulting in a sudden silence. I demonstrated this in a VW-engined ultralight to great effect; every morning my faint scars remind me of rearranging the dashboard in the ensuing forced landing. After my 40 stitches were removed I went back to Avgas.