Easy as pie.That is a very good observation lol. Well according to the poll it looks like 87 has the slight advantage. Reading the posts, it seems to be split in the middle....which still leaves me undecided hahaha
Run five tanks on 87 and five on 93, then five tanks on 91 non ethanol and report your findings.
But I think it should be done in summer weather where Ford says it's most noticable.
If you do I'll do it.