First of all, not a good choice with your almost new Altis 1.6 FL, maybe this leads to this grinding engine noise during cold startup in the first place. When switching to Total 5w30, have you used any kind of Engine oil flusher before pouring 5w30?
I also own Altis 1.6 FL and it's almost 46k on the ODO meter and never experienced such kind of grinding engine noise Alhamdolillah.
However, it's normal with Corolla Engines to produce such grinding noise but not such new engines to be precise, it usually happens when a car has been driven more than 100,000 kms or so and not kept with care.
My suggestion to you now is to let it go as if you go to the dealership again, they will just worsen it by doing some stuff here and there just to rip you off because that's what dealerships do usually with their unprofessional staff.
Anyways, if your engine performance and fuel average is great, then I suggest you let it go and not mess with anything that is not giving you any trouble.
