I always go with the 5k. It is very easy to tell when an oil change is
due....5,10,15 etc etc.
All I look at is the first couple of digits ot the odometer. If it is
divisible by 5 I do the oil change. Some may be a little less or a
little more than 5k actual miles. A lot of times if you try to do it
at at the exact interval you will end up forgetting about it all
together. that is much worse.
The machinery process of today, the filters themselves and the oil is
much better than the 70s and 80s. Anyone that reccomends that it be
changed more often, I question their motives.
All that being said, if you live in an extremely dusty environment,
you may need to do it more often, but I think that 5 k on the filter
and oil will work for 98% of the population.