My generator calls for 10W30 or Synthetic 5W30. I am assuming the calling for Synthetic 5W30 is for colder climate protection? My generator is stored on the veranda which is insulated and heated all year long. If I need it, I just wheel it out on the deck, fire it up, use it and when finished, I shut it down, wait a few minutes for it to cool, then wheel it back in to the house. I was able to acquire some very cheap Mobil 1 10W30 (they were out of stock on 5W30). I am assuming that this would be fine since the generator never sits in the cold for any length of time at all? Pour point or cold starting will never be an issue with it.