Ok, so I know there are multiple threads on what oil to use, I would like to post here my discoveries.
I have tried multiple oils in my 3. Mobil 1, Valvoline, Castrol Edge (which I have used the most). I often check my oil and do the old Biden sniff test.
All of the synthetics I have used have...
Great deal at Amazon for Castrol Edge Full Synthetic -- https://www.amazon.com/gp/product/B00JGQLZJ4/ref=od_aui_detailpages00?ie=UTF8&psc=1
Even if you get your oil changed, it might be worth buying and bringing it to the place that changes your oil. I bought 2 5qt jugs @ $19 USD per jug.
Of course Mazda doesn't "make" it's own oil as it's not in the oil refining business. Mazda outsources it's factory oil to some oil company. My belief is that it's Castrol. Has anyone looked into this?