I have read that a lot of people use 5w-30 in their cars here., but I haven't seen any info about how cold of a climate is too cold for considering this. The manual has a nice little diagram showing oil weights and the temperature range they are good for but it doesn't have 5w-30 on it. Does anyone know what the lower end of the temperature range is for 5w-30? I live in a climate there most winters I will have to drive at least one or two days with temps close to -20F, but other than that it stays around 5F in the winter. I also can't find anything other than amsoil 0w-30 in my area and wouldn't mind have the variety that comes with 5w-30 if it's safe in those temps.