[panzer dragoon]

my dad had this problem. Make sure you use 5W30 and not 10W30 oil. Make sure there is enough oil in the engine. My dad added 1 quart of Amsoil 0W synthetic (added when the engine was one quart low) and the noise went away. The rattling would go on at startup for 3-5 minutes then go away. My dad was using 5W30 and had the problem.

Amsoil and Mobil 1 are the only true synthetic oils I know about. Castrol Syntec is a cracked (split oil molecule by electricity) motor oil and not a true synthetic.