SHORT VERSION
Which Mobil 1 brand oil filter is correct for a 2013 Mazda3 iTouring SkyActive 2.0L: the M1-108 or the M1-102?

LONG VERSION
Went to change my oil for the first time today on my 2013 Mazda3 iTouring SkyActive 2.0L (had been doing dealership changes for a while, coupons ran out so doing it myself now).

I ordered a Mobil 1 replacement filter on Amazon - and here's where the trouble began. Amazon.com lets you filter products based on your car model, with a series of drop-down lists for your make, model, and trim. The trouble is, the last drop-down list are some DOHC engine variants that I don't confidently recognize and can't find listed any where in the manual.

I selected the "G" engine variant, assuming that since my manual *does* say SkyActiv-G some where in it, that the "G" must refer to the engine variant.

That led me to the M1-102.

...but then under the car installing the new filter, I noticed that it was a good 15% larger in diameter than the factory Mazda filter that was already on there (a Mazda K3804 ). I didn't try screwing on the threads, but the diameter was so far off I thought no way can this be right.

Headed to my local hardware store (Autozone), they look it up, and tell me it's the M1-108. I noticed while the clerk was looking up the model on his Autozone computer, he came across the same DOHC engine variant options as I had on Amazon. I asked him how he knew to pick whichever one he picked - he said **he didn't know**, but that "usually all the variants at that level use the same filter." I asked him to check the "G" variant on his computer, and he saw the same M1-102 I saw on Amazon - he had never seen that variation before.

Anyway, I took the M1-108, it was MUCH closer in diameter to the factory K3804 that had been on there, threads installed fine.

But I have this sense of paranoia that there's a chance maybe I should have still gone forward with the noticeably larger diameter M1-102...I don't know, am I going to break my car?

 

I learned else where that the M1-108 is the proper filter for my car.

I also found out that my engine type is actually variant "P", not G. This is indicated by the 8th digit of my VIN.