What's your oil change routine & methods?

[Coley]

...just wondering whatever everyone does for their oil change routine?

Do you base it on time?...ie...every 3 months (or 6 months? or?) regardless of mileage?
or do you base it solely on mileage?

How about additives?...I've seen some comments from the other thread about guys adding MMO to their oil changes?
What about zinc additives too? or choices for oil?...including best viscositys?
(note: I have the original flat tappet lifters in my stock 350 and I recently starting putting in a zinc additive based on the 'flattened lifter/lobe' issue that seems to crop here from time to time)

As well, I've heard comments about not filling the oil filter prior to installing it due to potential issues caused by.....??

...just wondering what everyone's recommended methods are, noting that I'm due for one here within a week or two.

All good
Coley