Originally posted by Level_7
You're kidding right? Some engines require high octane fuel in order to prevent premature detonation of the fuel/air mixture in the cylinder before spark ignition - this is usually the case in high compression or multi-valve (3 or more valves/cylinder) engines. Regarding your boyfriend's VR6, he should be running premium (his engine has a 10.1:1 compression ratio, pretty high for a V6) so he's probably running with a slight power loss and retarded timing and/or pinging/knocking occuring.
It's not significant to lose power when he's just using it as a daily driver. I was wrong though about him using 87, he uses atleast 91 but not 94+ as much anymore. Plus he lowered the compression in turbo-readying his engine. But he doesn't go to Sunoco just to fill up on 94 as much anymore (and I believe a place has 95 around here). Instead he just gets 91, unless of course he's racing. And as far as I know, he hasn't experienced any engine knocking on 91.