For what its worth, my SUV is supposed to receive premium, which is what I put in it. If I fill with 87, it just doesn't run as nicely, its noisier, has less power and gets poorer fuel economy. And it has the knock sensor and will retard the timing if it senses knock aka pre-ignition. Octane and regular vs. premium is one of the most common topics on automotive forums next to regular oil vs. synthetic.
Hey, now that oil has come up, is the Yamalube regular or synthetic? I would imagine that when I change the oil first time on my new GT, I will not think twice about using synthetic, I'm a firm believer....OK, verbal diarrhea episode completed.