1x/yr. with Valvoline Synpower in the Chili. That's not that many miles but it does start getting a bit dirty. Probably overkill.
5K miles in the 97 4Runner, dino oil. I do a lot of short trips to the bus stop, coupled with longer highway miles and little stop and go otherwise. Coincidentally my mileage has gone up as a result, 19-20mpg (new spark plugs helped...
Homer bucket for the used oil. O'Reilly's or wherever.