Both filters should be changed together.
I do mine ( 3500) at each oil change.
I order kits from genos.
Large kits that come with multiple fuel and oil filters.
I change oil and fuel around 15,000 km.
I use rotella t 5w40 year round ( 🇨🇦
The filters from genos are fleetgaurd. Look them up.
The bottom filter is your water separator, and the top is a finer filter.