Dealer won't use synthetic oil - 2022 CX-5 Turbo

[Buzzman12]

I've always run 10-30 in my newer cars.
Is there any harm in doing so with my 2022 non turbo mazda?

Depends where you are. I would not run a 10W anything up here in our Canadian winters.
The W stands for winter, and the first number (10 in this case) represents the viscosity when cold. The second number represents the viscosity when hot.
I like to run 0w30 in my cars up here. Easy starting, yet good protection when warm.
These new oils like 0w16 are nothing short of oily water.