This Ram 3.0L will be my first diesel so obviously I don't want to shorten it's lifespan. The diesel manual (downloaded) includes a chart showing the number of minutes to let the engine idle before shutdown. How important is this? Is this just a good idea in the long run or should we expect mechanical issues right away? Sounds a bit nit picky to me but never owned one before. What about short trips (5 min) to the store or work? Probably not enough time to warm up completely so probably don't worry about a 'cool down'?