In response to the question about how does the timing adjust to the fuel octane if it is higher than the designed (87) octane?
Asked my intructor at my local technical college, who is a retired Ford engineer/field engineer. He says on fords, i can't remember if it occurs when the engine is first cranked or if this occurs constantly (causing the erradic timing on the chart). The PCM slowly advances timing while reading the knock sensor inputs, as the timing is advanced and the knock sensor starts picking up pinging, it retards the timing a few degrees until the pinging is gone, and then advances the timing again about 2-3 degrees and that is how it determines the timing.
So a higher octane fuel would allow the PCM to advance the timing further without any knock sensor discrefencies (spell?) than a lower octane.