Originally Posted by JAJ
The annual oil change is called a "Low Mileage Service" and its covered by your regular four year factory-paid maintenance. However, your "every year at 10k miles" conclusion is not correct: you'll get it changed a year after the last change if you haven't hit the CBS limit, and again whenever the CBS indicator says to. They do not reset the CBS when they do a low mileage service - it just keeps running because too much other stuff is tied to it - air filters, cabin filters, differential and trans fluids, and so on. It's an out-of-sequence oil change that they pretend never happened.
For instance, I do about 7500 miles a year, so mine was changed at 1200 miles in April 2008, at 8,000 miles in April 2009 (a year after the 1200 mile change) and it'll be done eight months later in December 2009 at around 13,000 miles when the CBS says it's due. The next change after that will be a year later in December 2010 at 21,000 miles or so. And so on.
The CBS system supposedly monitors oil quality as one parameter. Why wouldn't an early change extend the normal interval? Or, does the oil "condition" have to get pretty bad (e.g. lots of short trips) to change the default 25,000 km interval?