Hit
Search Tab, upper right side of page; there are literally pages of threads
on the topic.
Fwiw, I have run tanks of 87 and, 89 on trips where that tank gets used in
a day, with zero ill effects in 8 1/2 years and 76k miles. Some here are 91/93
addicts, some of us run what we like. YMMV,
GL,mD