Cadillac 2007 STS Owner's Manual page 506

If the engine oil life system is ever reset
accidentally, you must service your vehicle within
3,000 miles (5 000 km) since your last service.
Remember to reset the oil life system whenever
the oil is changed. See Engine Oil Life System on
page 383 for information on the Engine Oil Life
System and resetting the system.
When the CHANGE ENGINE OIL SOON message
appears, certain services, checks, and inspections
are required. Required services are described
in the following for "Maintenance I" and
"Maintenance II." Generally, it is recommended
that your first service be Maintenance I, your
second service be Maintenance II, and that you
alternate Maintenance I and Maintenance II
thereafter. However, in some cases,
Maintenance II may be required more often.
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Maintenance I — Use Maintenance I if the
CHANGE ENGINE OIL SOON message comes on
within 10 months since the vehicle was purchased
or Maintenance II was performed.
Maintenance II — Use Maintenance II if the
previous service performed was Maintenance I.
Always use Maintenance II whenever the message
comes on 10 months or more since the last
service or if the message has not come on at all
for one year.