Your engine control unit adapts to the changes of octane running through the engine. I honestly have made 4000 mile road trips in the car on 87 and when i get back home i put 93/91 one back into it and its fine and over 80,000 miles of 87 into a supercharged mercedes that called for nothing but 91/93 and never had a problem.
I have heard from many engine mechanics that 87 has absolutely NO lasting negative effects on the engine besides temporary reduction of power and torque while it's in the tank.
But there are a lot of guys on here think its a cardinal sin and a slow death of the 86 to put 87 into the tank.
Would absolutely love it if some professionals in the field could clear the air when it comes to this.
