DFW area does have many Mazda dealers. The dealer I use, Town North Mazda, although is private owned, pl. their service department is decent. The service advisor I*m dealing with knows what I*m talking about, and familiar with most TSBs. Their parts department has Mazda moly in stock, so as non-value line parts such as Denso-made Thai oil filter. If you want moly for oil change, it*s $10 extra than regular Castrol*s.
This dealer uses one Mazda certified mechanic fixing everything I reported during my last warranty service. He screwed up certain things and got corrected by a master mechanic after I complained.
Yeah dealer service varies a lot and YMMV.