What brand of oil do the dealerships use in our vehicles? Do they all use one standard brand or do they vary from dealer to dealer?

 

I bought some 1L bottles at the dealership and they were "Mazda" branded.

 

I heard they use Petro Canada bulk! Is this true?

 

The oil they display is as stated, Mazda's house blend (one of the major manufactures probably makes it for them). However what they actually use may be another story. It's best just to do your own oil changes, that way you can know exactly what's going in there and how much of it.