Belt and oil questions

[Yaris17]

Hi all:

Since i am not mechanically inclined and question a serpentine belt breaking on a car I may buy,
What all on the yaris is controlled by the drive belt ?
Just the alternator and water pump ?

Also, if a car always has Amsoil synthetic , is it dangerous to go back and use valvoline oil ?

[vector9mm]

Don't know about the belt but you should be ok on the oil.

[Yesusk]

Also the compressor..guess Air conditioning, i read a post on the belt since mine is making noises :iono:, about the oil teh point is ..if you use mineral stay mineral, if you switch to sinthetic stay sinthethic, you can change from mineral to synt, but not reverse...