Engine oil Mobil or OEM FORD

M1 fs 0w40 has been working well for me. But this oil does lose some of its viscosity after a couple track days.

I buy mobile1 high mileage 20k mile oil and change it every year (less than 5k miles per year on my G coupe)

Mobil1 0W-30 full synthetic. Just did my first 1000-mile oil change a couple hundred miles ago. Been using Mobil1 0W-40 on my 2011 WRX for 220k miles, tracked, autocrossed, and daily driver duty after 160k miles when I had a head gasket failure and I rebuilt the engine.

If it says 5W-30 then the Hella synthetic should be fine. Except you can do all the other checks yourself. If they will use your parts that is ideal, get a Mazda filter and something like Pennzoil Ultra Platinum, Castrol or Mobil1 synthetic if you can get that.

I personally use Mobil1 exclusively with 5-30 regularly and sometimes go a bit heavier in the summer or if I'm planning on operating in 'Severe Service' conditions

Had my oil tested and it was recommended for 3500. I went with 3k as I do a lot of miles and use mobil 1 so my cost is relatively low.

Mobil1 every 6k like my owner’s manual says. Mine is stock. Blackstone says my oil would be able to go longer if I wanted.

2016 stock WRX here. 6k OCI's using Subaru filters and Mobil 1 5w-30 EP oil backed up by oil analysis. 90k miles presently.

I only use Mobil1 High mileage. Everytime I drop the oil at 100%, it feels less oily? Kinda less slippery? Definitely darker than I would like. My feeling is change it a little early.

I learned mobil 1 is the absolute worst oil to use in Subaru engines, especially ej257. Simply because it is good oil but because of the poor oil cooling the detergents burn in the engines causing premature wear.