engin knock

I was quite sure the days of a "master mechanic" over selling a problem was almost over. Especially over the internet where you have no possible monetary gain and should actually give advice. Your problem is nothing to worry about, you might want to use a thicker oil during the warmer seasons. What happens when you engine runs is the oil pump takes oil from the oil pan all the way up to the heads. When you shut off the engine the oil drains back down. So when you start your engine there is a lack of oil in the top end and you get valve clatter until oil returns and it goes away. Usually within a few seconds, new motors also have valve clatter even though you spend awhile priming the oil pump.