For the first four years of my 2009 Chevy Equinox, the dealer was doing it for a charge. Since I drive very little miles a year (less than 3,000), I now wait until the "oil life remaining" message shows 10% or less which could be over a year later. And I do my own oil changes, too. The higher Equinox ride height allows me to drain the oil and replace the filter without a lift or a jack. I do use Mobil 1 synthetic oil, which lasts long and protects the engine.
Changing oil will become as obsolete as changing spark plugs and setting ignition points. Newer synthetic oils are lasting over 24,000 miles, so a Volt can have its first oil change after five years or more!