It's about time for an oil and filter change on my 24 ft I/O with a
350 cid Mercruiser (salt water cooled).

Does anyone have opinions on who makes the best oil filters or are
they basically just a commodity item with all more or less equal?

Nest question: This is an old block with lots of hours but it still
runs well. I've always used straight 40 wt oil. Would it make any
sense at all to switch to a synthetic oil at this point, and if so,
which one?