What would cause the motor to make a knocking noise only when the engine is cold

I use 5W20 and there is no change. The motor only has 90000 miles on it. I have done timely oil changes the life of the car. It has been well maintained. Is there some kind of test or check for me to find out if it is the oil pump?

engine knock commonly atributed to resin and carbon build up. try ethanol treatment to a tank of premium fuel on next fill up. todays fuel uses ethanol blend which can leave build up in fuel delivery systems, combustion chambers and cause excessive wear to spark plugs. your fuel system needs a cleaning. if this helps, than make a point of treatment periodically(every oil change). you may need to pull spark plugs and regap them or replace them also.