Engine rattling after start when cold?

These engine had problems with the balance shafts but can I ask if you have a check engine light on? If so, we should run the codes, this will tell us what the problem maybe. Also, can you upload a short video of the noise? That way I can tell for sure what is wrong.

Here is a guide to go over in the meantime:

https://www.2carpros.com/articles/rattle-noise

I would make sure the engine oil is clean and full, if not change the engine oil and filter. Please go over this guide and get back to us.