Perhaps someone can educate me a little. What will a premium quality fuel do to help the dilution situation? Besides the obvious benefits of better combustion, less desposits, etc. It will still be direct injected and get past the piston rings. What am I missing?
Running premium most likely won't do much for the dilution problem. Some people argue that running premium results in less fuel in the oil because they reason that the engine will have a greater tendency to knock on regular gas, and the knock sensors will detect any knocking and the EFI system will adjust fueling, making it richer (injecting more fuel for cooling) to quell knocking. And some people figure that running premium will reduce overall knocking tendency, and allow the engine to run more lean overall. Personally, I feel that the driver's right foot has a lot more to do with it. For example, if you tend to shift early and lug it (my fiancÃ©e does this), the EFI is going to spray more fuel in at that moment in the effort to fight LSPI. OTOH, if you're lighter on the gas pedal at lower RPM, and hold your gears longer (which is better for an engine anyway, because engines hate lugging and need RPM to work efficiently), it should result in lower chances for LSPI events, and less fuel dilution.
We just use premium because it's a small-cube turbo engine and my fiancÃ©e tends to shift early (it's a 6-speed). May also have a minimal benefit for intake tract cleanliness and just overall engine cleanliness. But make no mistake, these engines are knock sensor-equipped, and can adjust for lower octane gas.