I live in S. Fl.... so warmer temp year round. I will soon own a 2014 Fiesta ST. I believe the manufacture recommends a 5w - 20 full synthetic... Isn't 20a little light for a turbo charged engine? In my mini cooper S with the 1.6L turbo I was told by my mechanic who specializes in such vehicles to use 5W-40 liquimoly in my turbo cooper vs 5W-30... why does the factory recommendation have such a low viscosity to a similar sized turbo engine in another car?