I have a moderately tuned turbo 2.0, and have it running slightly aggressive in ignition and cam timing. I run nothing less than 93 octane and always use Shell or Sunoco.
Last weekend I found myself in a location with only a BP nearby while doing some spirited back road driving. I filled up with their 93 and drove on. Within 10 miles I heard audible knock when running at high RPM and once I plugged in the scanner, I was seeing as much as 5 degrees KR where I had previously seen zero.
Its not the first time I've had a bad BP experience from multiple stations. What are your preferred brands and any opinions on BP?