When the engine is cold and its gets hot the rattling noise stop
When I start the engine there is a rattling noise on 2000 Dodge Grand Caravan
sounds like you could have lifter leaking down I would add some oil additive first
poss lifter noise or low oil level
Make sure you are using the correct weight oil, should be 5w-30. If you have not been doing oil changes on time the oil can also get sticky. It's recommended to change your oil about every 3,000 miles and to check your oil level each time you fill your fuel tank.