It's funny how attitudes towards oil change are different in different countries. In Germany, I would never go to the garage just for an oil change. We do an oil change either at the scheduled inspection, or when we're at the garage anyway (for winter tires) and the mechanic says it's time :-) which is about once a year.

My last car was a bit of a beater, and we did the oil change more frequently. Reason was that it had a problem with the transmission (manual, as most cars here), and from time to time there would be little metal shavings in the oil! But apparantly this is less horrible than it sounds, and somewhat normal for old cars. There is even a little magnet in the oil vessel to collect the shavings. After a combination of learning this, and having lived in the states for a couple of years, I insisted on changing the oil more regularly.