I doubt the manufacture has a different oil recommendation for So Cal  ...
The oil question has been put Mazda at many meetings I have attended .....
the answer that emerges lately is the change to 5W20 is mainly for fuel
mileage ..... it has a Ford engine and I think you will find most Ford
vehicles use 5W20 ....  I have also heard of other manufacturers switch to
5W20 ..... It seems like a small change in viscosity to affect fuel mileage
... but on the bigger scale it makes sense .... having said that if you had
a preference for a slightly heavier oil I doubt it would have any
detrimental affects ..... keeping the oil changed on schedule and keeping
the proper level is more important ....