Engine oil Mobil or PENNZOIL

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

I run Pennzoil or Motul depending on if I grab filters locally (Walmart for Pennz) or buy an oil change kit online (most use Motul). I would have no quarrels running Toyota's oil (Mobil 1), Subaru's Oil (Idemitsu), Valvoline, or any of the other reputable brands in my car

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.

have run penzz plat 5-30 for the entire life of the car almost, recently switched to the high mileage version as im pushing almost 150k miles on it.

I use mobile 1, 0-20w in my 5.3 GMC. 3k miles every change w filter. In the colder months it looks brand new coming out. Little bit darker maybe. My most recent change with the past month being 85+ I noticed it finally being very dark and red.

I only really noticed issues with oil consumption when I use mobil1, so I try to avoid that.