For the first couple years after I bought it (2006) I used to check it from time to time, using the dipstick. (I'd look at the digital gauge now and then, out of curiosity...but I mostly relied on the dipstick.) It was never ever lower than it had been the previous time I checked it, so I honestly don't check it all that often anymore. Although if I get underneath the car I can see the slightest hint of oil that I'm pretty sure is attributable to the RMS, I've never seen so much as a single drop of oil in the garage under this car.
Oil and filter changes at least annually, no more than 4-5k miles between changes.
69k miles on the odometer.