Engine oil Mobil or Shell

The oil type is likely fine, but the viscosity isn't. Ignore what the book says, get the 5W30 out of there. The PDs love to eat cams, and running 5W30 makes the problem worse. Me personally, I run Shell Rotella T6 5W40.

dude stick to the engine oil grade mentioned in the user manual and fill shell synthetic of that grade

Mobil 1 is my go-to... mostly because the level gauge on the side of the container is easier to read than any other brand. I've been using it in my 2018 since new and have never had an issue. Odometer is currently at 260,000.

Shell advance long ride or power you have two choices for fully synthetic trust me dude once you try shell there's no going back castrol is the worst for Royal Enfield and motul is better suited for high compression engines like KTM etc

I have a 2020 Corolla se with the 2.0l and I use 0w-16 from Mobil 1 which makes Toyotas oil for them.

Mobil 1 15w-50, Viton o-ring from any automotive or industrial supply house, Wix or NAPA(mfd by Wix) filter.

I use Mobil 1 15/50 in the engine, rotella t 15/40 in the primary, and Mobile 1 75/140 in the transmission.

I was using 0w20 because of price but got some mobile 1 deal 0w16 for cheap so I'll try that and see if I get better MPG (currently 35-42).

I will say I've done my last 3 oil changes with penzoil platinum and my engine rode rougher and louder than it did before with the Toyota oem oil. So this past time I tried mobil 1 and it's way quieter and rives smoother.

I have been running Mobil 1 0w-40 since new with over 50k miles on different Big turbo(80k total miles) setups and always replacing seals and gaskets due to oil leaks(its some really thin oil).