Some people think that a lot of metal particles and assorted gunk
collect during the break-in period, so they get the oil changed
at around 500-1500 miles, or 800-2400 km.  You should then follow 
the schedule in your owner's manual (every 7500 miles (12000 km) 
for regular service, or every 3750 miles (6000 km) for severe service)
as the minimum oil change interval. The extra oil change is considered 
by many to be cheap insurance.  Also, average driving often falls 
under "severe" conditions that require more frequent oil changes.

The manual recommends using 5W-30 or 10W-30 SG oil, depending on
the expected temperature during the oil's service life.  The 10W-30
should not be used under extreme cold conditions (below 0 F).  You 
can use a conventional oil, or synthetic.  Synthetic oil has better 
heat and cold handling characteristics, and resists viscosity 
breakdown much better than conventional oil, but is significantly 
more expensive.