Interesting. Perhaps how the vehicle is used contributes to fuel dilution. My 2008.5 Speed3 is very hard on oil with a four mile commute. The oil is dark black and reeks of gasoline after a couple thousand miles. UOAs show 2-2.5% fuel and low viscosity. I am especially concerned about the latter after Mazda's service advisory against anything less than 5W-30. I like to run an HTO-06 rated oil like M1 or PP. This last time I mixed in one quart of 0W-40 to try to beef it up a little. I really am not comfortable going much beyond 4,000 OCI with the way this engine is used.
Originally Posted By: MCompact
The DI motor in my Mazdaspeed 3 gets a 7,500 mile OCI using M1 5W-30. UOAs indicate no issues with wear or fuel dilution; Blackstone even suggested trying a 10,000 mile run, but I'm sticking with the OEM interval.