No real secrets- I just stay on top of scheduled maintenance. I don't baby the car but I don't constantly hammer on it either.
I installed a Mazdaspeed CAI at 43,243 and a Hypertech tune at 135,545.
No significant fuel dilution or oil shearing.
For some reason Mobil 1 gets bad mouthed quite a bit on a few of the Mazda boards but it has certainly served me well in this-and several other-applications.