Change her oil and filter every 12 months if she stays under 4-5k miles per year.
Walmart sells quality higher milage synthetics (Penzoil, M1, Castrol) for less that $23 for a 5 qt. jug. You probably know this already.
I do all of ours myself. The Accord and the Cooper get a shit ton of miles (commuters) so they are once a month. The others (JLU, older Chevy and X1) get much less so I do them at 3-4k miles. Unless it I really cold I enjoy doing them. When it is REALLY cold I just have Walmart do the change (with my filter) and then I check everything when I get it back. Always check the oil level after someone else does the change. For instance, our Wrangler (JLU) is a hybrid. The engine takes less oil than the long used and way more common Pentastar V6. Last winter I had to drain over a quart out when I got it home. They used the Pentastar spec I am sure...