We just purchased both a new Insight and a new Fit and we do drive in the Phoenix metro area, so we are in an extreme climate at least five months a year.
The service adviser, who was one of the reasons we bought two cars from that dealership because he is that good, made sure to tell me that I should forget the old 3,000 mile/ 3-4 month rule and drive the cars until they say 5% remaining and then get them in at that point. He said anything else is wasting a natural resource due to a premature change and that did include the initial tank of oil.
The service adviser, who was one of the reasons we bought two cars from that dealership because he is that good, made sure to tell me that I should forget the old 3,000 mile/ 3-4 month rule and drive the cars until they say 5% remaining and then get them in at that point. He said anything else is wasting a natural resource due to a premature change and that did include the initial tank of oil.