Engine oil Shell or OEM Mazda

I have a buddy that used the Shell Rotella diesel oil that is dirt cheap for his 2009 r1.

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'm at 365,000 km and switched to Shell Rotella T6 probably 30-40k ago. Oil consumption was at last halved - the detergents in that oil really help clean up deposits in the rings, or so I'm told.

Quality synthetic oils provide the lowest oil temps, longest running life and superior lubrication. I use Shell Rotella T5 10W-40 for Texas climate.

I've used T6 in my MK4 BEW for 5 years now. Regular changes, no issues at all, and at 1/3, the cost of 'suggested' brand.

Personally I rock she’ll rotella 15w40 in the summer and 5w40 in the winter to aid in cold starting. Seems to work pretty good

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.

Shell helix has been fine for me

As long as you’re not mixing fuel with it you’ll be fine. All of my stuff runs on basic and cheap T4 Rotella 15w-40. Have never had a single issue

Rotella T6 full synthetic, zero problems, never let me down.