I got a pretty generic response from Mazda regarding the UOA.
Quote:
Hello Derek,
Thank you for contacting Mazda.
We would not recommend using any other viscosity of oil than what is stated in your owner's manual. We would also suggest taking note of the mileage you perform your oil changes and keep receipts of your the oil purchase for the vehicle as mentioned in your warranty booklet.
If you have any further questions, please do not hesitate to give us a call at the number below.
Best Regards,
Dan
Customer Assistance Representative
Mazda North American Operations
(800) 222-5500, X1178
I guess I will continue using 0W-20 (trying their new kind next time) and continue to keep records of all my oil changes and receipts.
Derek