I have a 2017 Nissan Frontier with the 6 cyl engine, with 27000 miles on it. I bought it used with about 17000 on it. I think maybe it has always had this noise, but it has kinda started to annoy me lately. Anyway, it is a fast rattle sound that lasts one or at most 2 seconds when first starting the engine if the engine is not warm. Also much more noticeable and longer, as in up to 2 seconds after the truck has been sitting a few days, as opposed to using it every day. Probably why I notice it more now, because it used to get driven every day, but now with the Covid stuff neither me or my wife, as we are retired, are hardly driving, and it will sit a week or more at a time. I am thinking it has something to do with the cam chain, but this is the first vehicle I have had with cam chains, or at least I think so. SO, I guess my question is, should I just ignore it, or tell my dealer? My nearest dealer is 50 miles away. OH, by the way, I am using QS ultra 5/30 which has about 800 miles on it , and a Fram Ultra filter which has about 3000 miles on it. And it is clean and full.