Hello, thank you for choosing Just Answer. My name is XXXXX XXXXX X will help with your engine noise upon start up.

My best advice is to get the vehicle to a repair shop to determine exactly what is causing the rattle. It could be something sinister, such as a timing chain, that needs to be addressed.

With that said, I expect it is just hydraulic lifters that loose their prime as the car sits. When you start the engine, the valve train makes noise as a result of the slack. After oil pressure is created (a few moments after starting) the lifters self adjust and the noise goes away.

If this is indeed the case, there are two things to try. First, it is possible that the valve lash needs to be adjusted. This is somewhat labor intensive and should be done by a qualified mechanic. Before doing this, I would suggest simply changing the oil to a more viscous variety. If you are using 5W-30, move up to 10W-30. If you are using 10W-30, try 15W-40. Often times, as engines age, they require greater oil viscosity to maintain the same level of performance as when new.

I hope my answer is helpful. Let me know if you have any additional questions.

Best Regards,
Stephen