With owning 2 of the MAZDA 2.5 offerings, one the true MZR and one being a SKYACTIVE, Just go to a EURO 0-30 and sleep well.
I switched our CX-5 over very early to a UERO 0-30 and it made an immediate circumstantial difference, with maybe .5 mpg loss. I have not done a UOA on the CX-5 yet with the 0-30, and I may not. I did with the same oil in a 5-20. When the 0-30 went in it improved on fuel dilution, uses NO oil now between OCI's and it used @1/2qt between OCI's since it was new. The 30wt seems and feels quieter and smoother and it just makes me feel much better in a DI engine where the wife uses remote start in the winter (longer idle times)!! Again, I have not done a UOA on the 30wt, I'm not sure I have a reason to considering the lower viscosity version of this AMSOIL gave me a solid UOA a few years back.
In my 3, I had the same experience although it was a higher mileage vehicle (today its at 300k and runs like it has 30k on it, I love this car). I switched it to a GC in 0-30 and my oil usage went away immediately. I eventually went to a 0-40 GC blend in that car with amazing results and solid UOA's out to 7500 mi. I just add 2qts of 0-40 during an oil change and the MZR loves it. I did not use AMSOIL in the 3, only GC. Prior to the GC I tried using PP. I never did a UOA on the PP but it would use OVER a qt per 5000mi OCI. I went to GC 0-30 and it never used oil between OCIs again, still don't to this day with 300k mi on it I try to stick to 7500 OCI's depending on the use case.
So allot of anecdotal and circumstantial comments in my post, I think I do have a UOA on here for my MZR, but at the end of the day.... I would ALWAYS run a UERO oil in that 2.5 engine!