In a recent comment by Dude under the title of 'To flush or not to flush' there was useful logical advice on that topic.
I'm not so sure that his comment on semi-synthetic oil being a rip-off holds water. S-s oils are widely used by reputable service stations for oil changes and it was only when my YRV came out of warranty and I started servicing it myself that I changed to fully-synthetic. I can't say there has been any noticeable improvement, but I trust that the extra cost should bring some benefit.
My 'noticeable' observation on oil type relates to my Moto Morini 350cc twin motorcycle. It has a simple robust engine with no pressure feed to the rockers. Oil mist passes up the push rod tunnels, condenses on the inside of the rb cover and drips down from strategically placed 'crows feet' onto the rockers. Using the Castrol mineral oil traditionally used for this engine I found severe rocker face wear. I changed to fully-synthetic and the wear was almost totally banished. Out of interest I then changed to s-s and the wear rate remained the same as for f-s oil. As there was no wear benefit by using f-s instead of s-s I now stick with the latter - at much less cost.
And no, I don't have shares in Comma, by which I swear!