Some vehicles around Phoenix come from the factory filled with synthetic oil and the recommendation to use it for life. The safe bet is to always use what the factory recommends. The recommendation is what’s been proven to work in function and durability tests. The recommended oil is also a factor in determining oil change interval schedules.
A good quality oil has more additives that are engineered to clean and protect the engine. They cost a bit more, but are worth the extra protection. If you buy budget oil, you might want to consider shortening your oil change interval.
Sometimes fluids are developed specifically to meet the needs of a particular family of engines. An example would be coolant. Because of the different materials used to build the cooling system, the coolant has to be formulated to protect those parts, which vary from manufacturer to manufacturer, from corrosion. We’ve seen special coolant in Phoenix for General Motors, Volkswagen, Chrysler and others.