There was a time back in the early 2000's where Shell had to pay for damaged fuel sending units on customer's vehicles due to damage that an additive caused. The vehicle would indicate a higher level of fuel remaining while the tank was in fact empty. As for Esso in Canada, they took longer than the others to get their sulphur content in line with CDN standards, This caused cars to stink of rotten eggs if driven multiple short distances. Both conditions above have been corrected.
I manage a fleet of several thousand vehicles and we do not see these problems anymore, however I typically make it a point to drive past Esso, due to how they handled the Valdese oil leak in Alaska where they ruined thousand of lives and appelled the ruling to pay higher compensation to those that lost their livelihoods. The actually pay out would have been less than one day's profit had they adhered to the ruling.
As for using higher Octane, I recall a bulletin that came out on the 2000 MPV. It advised against the use of 92 octane when 87 was required. It caused a "hard start" condition. To better understand octane, the higher the fuel octane, the greater the compression needed to ignite the fuel. If your vehicle is designed to use 87 octane, it will spark at the designated compression. As 92 is less volatile, the 87 spark will be too soon and you will not get the required detonation to provide power and to burn all the 92 fuel in the chamber. In a nutshell, on todays cars, you are wasting your money on 92 octane unless it is specified. In our fleet, drivers buy 92 octane to get double reward miles at the pump. Our fuel card provider send alerts to fleet management when "super" is purchased. Each time the driver swiped a rewards card to get the extra points causing more cost to the bottom line. Needless to say, big brother gets on them ASAP. There is no benefit to a 87 octane vehicle other than making the fuel companies richer and doubling the reward miles.
