When I didnt drive much I would change oil minimum twice a year, usually in autumn - 5W30 for winter and then in spring 10w30 for summer season. The manual suggests 5W30, but I just know the 10 wont become as thin in hot summer, esp. when you overload an engine with AC while standing in traffic. The result? I got 272,000km and the engine still purrs.
Now I have to change oil more than 4 times a year and I go by 5k intervals.
By the way there is no such thing as 16k service for oil, that could be scheduled but not a regular service.
Today I put in a Napa filter which is supposed to be Wix, surprisingly it cost the same as Fram.