Boutique oils are generally over priced oils sold to 'true believer' customers.
Some are top notch oils, but that level of product is rarely, if ever, necessary.
Amsoil, Red Line, Shaffer's, and perhaps Royal Purple and a few more are
generally good products. I've seen some boutique oils by unknown blenders
that aren't over priced, but not worth taking a chance on.
Most especially motorcycle oils.