When I start the engine first thing in the morning it makes a clattering sound,until it runs for a minute

The clattering is most likely valves rattling until the oil gets up to top of engine,recommend change the oil and filter,use a good filter like fram oil filter,i've always used castrol 30 weight oil in winter,then summer 40 weight, also recommend you add lucas oil treatment,1 bottle,add with your oil change for top end lubrication,the oil stays and clings onto valves and adds a whole lot more of top end lubrication to your engine than just regular oil.it's just a treatment,i have a 1994 ford explorer with 450.000 miles on it.just trying to see how far i can go with original motor.but i always use castrol oil,fram oil filter and always add lucas oil treatment every time i change my oil.thank you for choosing fixya.com good luck!