Fill with premium, the ping stops, timing is advanced, power and fuel economy improve.

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I like the challenge of your hypothetical. Well yes and no on your hypothetical - here is my take on it: First off it does not follow the owners manual. The owners manual says when to replace the injectors and reset the engine electronics. Second, if it starts to ping you know it needs tuneup - if it does not ping you feel the loss power. The check engine light would probably be on in this situation. The injectors have to pretty old and dirty for the engine to ping. Third, putting premium will bring back some power and fuel economy, but not to the original level with clean injectors, reset electronics and regular gas.

I stay away from the semi-synthetic or full synthetic oil. I do the oil/filter changes at 5K or annual which ever comes first. Personally I think 3K is too often. My VOLVO owners manual says 5K. My Mercedes Benz (diesel) owners manual says 5K. I do the same 5K for my Ford F250 and Dodge Ram 2500. All my vehicles are between 150K & 250K so it works for me. But then it isn't the cost of the oil change as much as the hassle for me with 5 vehicles.

jaagu