As stated before climate has alot to do with it, 0-W flow characteristics are better for colder climates. Keep in mind these cars are manufactured in Europe where the climate seems to be much colder. Course couldn't bank on that being as I saw some -40's on the six o'clock news from N. Mich !!! Much too cold for my Texan blood !
5W-30 should not do any harm what so ever even tho it's not the recommended !