My friend has a Honda HS720AS and his manual calls for a 5w20 or a 5w30. It will be in use in Colorado where it can get way below zero. Do you think a Ow30 like German Castrol or Mobil 1 0w30 would be a better choice then what the book calls for? I have been using German Castrol 0w30 in my 30 year old Craftsman snow blower with good results. Thanks for any input!