[Chippy Minton]

Sorry. It's your choice after all. Let's put it this way.
I will not be using SM oil in my Model A engine because it does not contain a vital additive and will cause harm. I am going to continue to use SL as my researches have shown to be more suitable.
You are free to do as you choose. Hopefully others will check before following either recommendation.
This might be a starting place;