Originally Posted By: SilverFusion2010
I don't know that anyone has done scientific testing with this but yes I think premium could reduce fuel dilution.
1. High compression DI engines are set to run rich on 87 to reduce knock, specifically LSPI.
2. If we assume the ECU/PCM is programmed to utilize the knock sensors to control ignition timing, then logically the engine has an idea of the knock resistance of the current fuel.
3. This could be used to set thresholds for safe fuel mix. ECU sees higher octane fuel, and advances ignition timing and leans out the air/fuel mix, resulting in less fuel injected.
4. Less fuel injected means less fuel to leak past the rings and dilute the oil.
I can't say regarding oil consumption. It is possible that the engine has been consuming oil the entire time and fuel was maintaining the level. Now that you have less fuel dilution (theoretically), you're seeing the level drop.
Yes, I believe this to be the most likely. Most OEMs are probably playing with the timing and fueling constantly to get the most efficiency from these engines, running right on the knock threshold.
High compressio, Forced induction DI engines are likely running rich on 87 in order to combat knock. It makes sense to me then that feeding it high octane may well prevent fuel dilution.