Buick 2004 Park Avenue Owner's Manual page 372

100,000 Miles (166 000 km)
Inspect spark plug wires. An Emission Control
Service.
Replace spark plugs. An Emission Control Service.
Change automatic transaxle fluid and filter if the
vehicle is mainly driven under one or more of
these conditions:
− In heavy city traffic where the outside
temperature regularly reaches 90°F (32°C) or
higher.
− In hilly or mountainous terrain.
− When doing frequent trailer towing.
− Uses such as found in taxi, police or delivery
service.
If you haven't used your vehicle under severe service
conditions listed previously and, therefore, haven't
changed your automatic transaxle fluid, change both
the fluid and filter.
6-18
150,000 Miles (240 000 km)
Drain, flush and refill cooling system (or every
60 months since last service, whichever occurs first).
See Engine Coolant on page 5-25 for what to use.
Inspect hoses. Clean radiator, condenser, pressure
cap and neck. Pressure test the cooling system
and pressure cap. An Emission Control Service.
Inspect engine accessory drive belt. An Emission
Control Service.