I'm not sure that early oil changes have any benefit when it comes to fuel dilution. According to this study on fuel dilution in direct injection engines (2002), fuel dilution almost reaches a steady state level within a few hours of engine operation. From there it will rise when conditions for dilution are favorable (cold engine, high engine load), and then drop when conditions for dilution are unfavorable (warm oil/coolant, low to moderate engine load) as the fuel vaporizes from the oil.
The figure below shows fuel dilution in an engine operating with 40 degree C coolant/oil temperature for 10 hours, followed by 10 hours of 80 degree C coolant/oil temperature, with moderate engine load at 2000 rpm:
Within two hours of "highway cruising" conditions, dilution drops from over 7% to under 3%, and drops further to 1% after 10 hours. I'd expect that some of the heavier components of the fuel will never evaporate. This is not obvious in the 20 hour test, but might be in a 100+ hour test.
The best way to combat fuel dilution is to avoid short trips with a cold engine. High engine torque increases fuel dilution a lot as well since the injectors are firing for a long time while the piston is travelling far down into the bore, washing the cylinder walls with fuel.
Preheating the engine with a block heater in the winter, and using a grill block to reduce warmup time and increase steady state oil temperatures should help as well.
A functioning PCV system should better allow fuel vapour to escape from the crankcase.
The figure below shows fuel dilution in an engine operating with 40 degree C coolant/oil temperature for 10 hours, followed by 10 hours of 80 degree C coolant/oil temperature, with moderate engine load at 2000 rpm:
Within two hours of "highway cruising" conditions, dilution drops from over 7% to under 3%, and drops further to 1% after 10 hours. I'd expect that some of the heavier components of the fuel will never evaporate. This is not obvious in the 20 hour test, but might be in a 100+ hour test.
The best way to combat fuel dilution is to avoid short trips with a cold engine. High engine torque increases fuel dilution a lot as well since the injectors are firing for a long time while the piston is travelling far down into the bore, washing the cylinder walls with fuel.
Preheating the engine with a block heater in the winter, and using a grill block to reduce warmup time and increase steady state oil temperatures should help as well.
A functioning PCV system should better allow fuel vapour to escape from the crankcase.