I have never seen an Owners manual that tells you to use 87 octane fuel. Every motorized vehicle I have ever owned has said use a MINIMUM of 87 octane, or whatever the number may be. My vote is for the highest octane. I know for a fact that I get better gas mileage running high verses low and much better performance. I would also have to argue the High oct burns cooler than low. Back in my po boy days when I drove a 78 trans am, I lost the heater core. Didn't have the money to replace it and for some reason was driving around with about a 6"x 8" hole in the fire wall where the old core was mounted. It was winter time and I used the heat off the motor to get by, seaping through the hole. Long story short, when I burnt 92 oct compared to 87 that engine put out more heat burning 92 octane. IMHO, I say high octane burns cleaner hotter and you use less per mile.