I bought an '06 Mazda 3s 5-Door GT (LOADED!!) with the 2.3L motor. It's spec'd for 5w-20, and that's what I'm going to use.....No Exceptions!!
Anyway, I bought 8 liters of Torco SR-1 5w-20 from the Torco website. That's pretty cool, just click and like magic the oil is at your door in 2 days...