Engine oil OEM Mazda or MOTUL

Motul 8100 x-clean 5W40 seems to be the sweet spot, all of my friends drive it in EA113/EA888 engines.

Other Euro brands such as Castrol or Motul are also fine choices

I bought a Mazda CX-5 dealer test car with 300 Km's on it back in 2015 when I moved up to Osaka. I drive a LOT and was getting the oil changed roughly every 5000 km's per Mazda's recommendation.

I used Motul and it made shifting noticeably better

I used the Kawasaki 10w-40 for the first year I rode mine, it would always have an odd mis shift here and there. Last year I used Motul 7100 and it made a huge difference, way less shifting issues

If you are considering an oil additive, best practice is to instead use higher quality oil (I like motul) and select one which matches your use case.

I use Mazda's weight recommendation for my environment, as illustrated in your owners manual. I use 10W-30 and 15W-40 Full-Synthetic oils with zinc additives to stave off carbon deposits.

I've been using Motul for hybrid cars.

Well after the second oil change in the dealer I decided to look a external place to change my VN oil but I just bring everything and since then I use Motul 5w-30, no issues so far, a bit expensive but I dont care.

Motul 5w40 every 3500ish miles