Unfortunately I received this "advice" a day after I topped off with premium so I have yet to run the test. I am skeptical, especially since the noises I hear are somewhat different than any other pinging I have heard before. But as I get older I find that I must just give things a try. I find the more I learn, the less I seem to "know". I will report my findings as soon as I can. My friend who took the advice said it did work! He suspected it had to do with the engine control software... Honestly I wouldn't be surprised. Another factor could be that here in Seattle at least, our gas has 10% Ethanol. And the premium is 92 not 91 so I don't know if any of that could be an issue. The dealer tech said this info came from the regional service manager.

Mike

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra