Have used Chevron in all my bikes & cars since 2005, no problem (in this time-frame Shell's personal second choice when Chevron scarce)... As we all know, fuel companies introduce new formula/ types every so often (more or less detergent, oxygenation, MBTE [banned?], ethanol, flex-fuel, etc.), creating great debate about whose best, which really boil's down to personal preference to some degree?
In my limited experience of determining highest fuel quality, bikes (having smaller, most temperamental high compression engines) are best indicator. Basically, if it makes good smooth power there, it's good elsewhere (eliminating detailed analysis - ha ha)... So currently, the seat of the pants results are: Chevron over last 5 years (it's vacillated over past 20 years from Shell, 76, Mobil, Chevron... back & forth roughly in that order). 91 Octane on all...
The common denominator among personal conversations with various fuel haulers over the years is all fuel (regardless of brand) basically comes from same refinery. It's the fuel "formula" which may vary from brand to brand. As an aside, different haulers have also advised to maintain receipts on fuel purchases for the lesser known purpose of determining if (and what) fuel a contributing factor to engine failure (lab tests could determine percentage of engine failure attributed to problem fuel, with potential compensation from supplier). This makes sense to me, especially if using the same gas fairly consistently, and especially if water or incorrect formula proven.
