Hey Eiron,
Do note that I'm a n00b at this.
First off the main reason I'm doing this, is because its a brand spanking new car thats under the 5w-20 requirement...not an older model car that was recently switched from 5w-30 to 5w-20.
This of course could actually mean the mazda internals are actually designed for a lighter weigh oil. I didn't think anything of it till a fellow forum member switched from the 5w-30 he was running to 0w-20 and noticed a difference in how smoothly the engine rev'd.
So I decided to begin reading on the various types and doing research.
So here I am going to try 0w-20 for awhile and see if I notice a difference. Of note is, that both the Mobil1 5w-30 and 0w-20 both offer superior protection to the syn blend 5w-20's.
The oil changes I'm doing are...
At 1000
At 2000
At 5000
I changed the oil and filter at 1,000 and will be changing the filter again at 5,000, then every 5,000 from then.
Then every 5,000 from there with a UOA at the 5k mark for the 0w-20.
Of course if anyone who knows better has any suggestions, please bump in.