Engine oil Mobil or Shell

It's perfectly fine for the WRX, and it's what I use in mine, as well as its two previous owners. My car's maintenance records include two reports from Blackstone Labs detailing their examination of the Rotella T6 5W-40 oil and according to those the engine has worn very well on that oil

I personally swapped from 5w-30 in my OBXT to T6 5w-40 and have noticed a decrease in oil consumption (newish engine with 28k so that also helps).

I've used it, no problems

Yes that's what I've been using for my 2020 hybrid.

Mobil 1 0w-30 AFE has the correct certification, I just used that. Easy to find.

This is a late response but I just saw your post and it's exactly what happened to me when I took my 2018 GSW 1.8 TSI 4Mo in for the 20k mi service. They filled it with 508 00 0W-20. I didn't catch it until much later and I changed the oil myself at 27k mi with Mobil 1 502 00 VW approved 0W-40 oil.

I did my own oil/filter change at 27k mi with Mobil One European Formula 0W-40, since I'm a little uneasy about 10k intervals in So Ca stop and go traffic and 100+ F heat.

I've been using 0W40 Euro Formula from Mobil 1 for years in both my cars. You will be fine running it.

As a Mercedes-Benz guy, I've used Mobil One European Formula 0w40 in them for decades. It is very good oil. I have well over a million miles on Mercedes-Benz cars using that oil with the extended (10K-15K mile) change interval with zero issues. Several of my cars have gone over 200,000 miles.

I run Rotella T6 5-40 on my VR6 and also an 850 Turbo.