I have a 2016 cx-9 sig. I have done all of the maintenance myself minus the valve cleaning. I'm currently sitting at 75k miles. I have noticed some things about this engine. It is very similar to my old Mazdaspeed Miata. What I mean is it goes through spark plugs. I changed mine late at 52k miles. I checked them just now, and the porcelain is roasted. I also just drove to southern Michigan and back from the Florida panhandle. My oil smell strong of gasoline, I will be changing the oil, and the plugs. My hopes are to install a oil catch can this year. I will be changing the plugs every 25k miles, and oil every 3500 from now on.