Well, I have to chime in a bit here. Seems we are all taking sides.
Some of you proclaim to not doing oil changes until 20K miles, or beyond. Wow, just wow.
Then there's the other side of the argument where oil changes are being done too soon.
I'm old school (in my 60's), and would never run an engine past 10K miles without an oil change.
Yes, oil has gotten better, and I have jumped on the Mobil 1 synthetic bandwagon with my Nissans.
However, being anal and everything, I still change my oil between 6,000-7,000 KMS (not miles). That's about 4,000 miles at the most.
My pathfinder is 15 years old with 312,000 kms on it. Still purrs like a kitten. No oil leaks or burning.
For the extra money I've spent, I get a clean engine and peace of mind.
I'm also a big advocate for replacing factory oil on a new car as early as 3,000 kms, if not sooner.
I'm waiting to take delivery of my new 2107 Mazda 6 (I'm out of the country at the moment. More on that in another post).
I will not be waiting very long to do my first oil change when the time comes. Don't care what the user manual says.
I guess in summary, I tend to be on Molester's side more than some of you other folks.
If you feel confident about running 20K or more on the same oil, then great. Personally, no way.