engine oil BUICK CENTURY 1998 User Guide

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6-10
3800 Supercharged V6 (L67) Engine
When you open the hood on the 3800 Supercharged engine, here's what you will see:
A. Windshield Washer
Fluid Reservoir
B. Remote Positive
Battery Terminal
C. Radiator Pressure CapD. Engine Oil Dipstick
E. Oil Fill Cap
F. Automatic Transaxle
Fluid DipstickG. Brake Master Cylinder
H. Engine Coolant Recovery Tank
I. Air Cleaner

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6-11
Your vehicle has a 3800 Supercharged V6 engine. The
supercharger is a device designed to pump more air into
the engine than it would normally use. This air, mixed
with fuel, creates increased engine power. Since the
supercharger is a pump and is driven from an engine
accessory drive belt, increased pressure is available at
all driving conditions.
The Powertrain Control Module (PCM) works with a
vacuum control to regulate the increased pressure
required during specific driving conditions. When this
increased pressure or boost is not desired, such as during
idling and light throttle cruising, the excess air that the
supercharger is pumping is routed through a bypass. All
of these controls working together provide high
performance, character and fuel efficiency in the 3800
V6 Supercharged engine.
Engine Oil
If the CHECK OIL LEVEL
light on the instrument
panel comes on, it means
you need to check your
engine oil level right away.For more information, see ªCheck Oil Level Lightº in
the Index. You should check your engine oil level
regularly; this is an added reminder.
It's a good idea to check your engine oil every time you
get fuel. In order to get an accurate reading, the oil must
be warm and the vehicle must be on level ground.
The engine oil dipstick is a
round, yellow loop located
directly behind the
engine fan.
Turn off the engine and give
the oil several minutes to
drain back into the oil pan.
If you don't, the oil dipstick
might not show the
actual level.

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6-12 Checking Engine Oil
Pull out the dipstick and clean it with a paper towel or
cloth, then push it back in all the way. Remove it again,
keeping the tip down, and check the level.
When to Add Engine Oil
If the oil is at or below the ADD mark, then you'll need
to add at least one quart of oil. But you must use the
right kind. This part explains what kind of oil to use. For
crankcase capacity, see ªCapacities and Specificationsº
in the Index.
NOTICE:
Don't add too much oil. If your engine has so
much oil that the oil level gets above the
cross
-hatched area that shows the proper
operating range, your engine could be damaged.
Add engine oil at the engine oil fill cap next to the
oil dipstick.
Be sure to fill it enough to put the level somewhere in
the proper operating range. Push the dipstick all the way
back in when you're through.

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6-13 What Kind of Engine Oil to Use
Oils recommended for your vehicle can be identified by
looking for the ªStarburstº symbol. This symbol
indicates that the oil has been certified by the American
Petroleum Institute (API). Do not use any oil which
does not carry this Starburst symbol.
If you change your own oil,
be sure you use oil that has
the Starburst symbol on the
front of the oil container. If
you have your oil changed
for you, be sure the oil put
into your engine is
American Petroleum
Institute certified for
gasoline engines.
You should also use the proper viscosity oil for your
vehicle, as shown in the following chart:

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6-14
As shown in the chart, SAE 10W-30 is best for your
vehicle. However, you can use SAE 5W
-30 if it's going
to be colder than 60F (16C) before your next oil
change. When it's very cold, you should use SAE
5W
-30. These numbers on an oil container show its
viscosity, or thickness. Do not use other viscosity oils,
such as SAE 20W
-50.
NOTICE:
Use only engine oil with the American Petroleum
Institute Certified For Gasoline Engines
ªStarburstº symbol. Failure to use the
recommended oil can result in engine damage not
covered by your warranty.
GM Goodwrench oil meets all the requirements for
your vehicle.
If you are in an area where the temperature falls below
-20F (-29C), consider using either an SAE 5W-30
synthetic oil or an SAE 0W
-30 oil. Both will provide
easier cold starting and better protection for your engine
at extremely low temperatures.
Engine Oil Additives
Don't add anything to your oil. Your dealer is ready to
advise if you think something should be added.
When to Change Engine Oil
If any one of these is true for you, use the short trip/city
maintenance schedule:

Most trips are less than 5 to 10 miles (8 to 16 km).
This is particularly important when outside
temperatures are below freezing.

Most trips include extensive idling (such as frequent
driving in stop
-and-go traffic).

Most trips are through dusty areas.

You frequently tow a trailer or use a carrier on top of
your vehicle.

The vehicle is used for delivery service, police, taxi
or other commercial application.
Driving under these conditions causes engine oil to
break down sooner. If any one of these is true for your
vehicle, then you need to change your oil and filter
every 3,000 miles (5 000 km) or 3 months
-- whichever
occurs first.

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6-15
If none of them is true, use the long trip/highway
maintenance schedule. Change the oil and filter every
7,500 miles (12 500 km) or 12 months
-- whichever
occurs first. Driving a vehicle with a fully warmed
engine under highway conditions causes engine oil to
break down slower.
What to Do with Used Oil
Did you know that used engine oil contains certain
elements that may be unhealthy for your skin and could
even cause cancer? Don't let used oil stay on your skin
for very long. Clean your skin and nails with soap and
water, or a good hand cleaner. Wash or properly throw
away clothing or rags containing used engine oil. (See
the manufacturer's warnings about the use and disposal
of oil products.)
Used oil can be a real threat to the environment. If you
change your own oil, be sure to drain all free
-flowing oil
from the filter before disposal. Don't ever dispose of oil
by putting it in the trash, pouring it on the ground, into
sewers, or into streams or bodies of water. Instead,
recycle it by taking it to a place that collects used oil. If
you have a problem properly disposing of your used oil,
ask your dealer, a service station or a local recycling
center for help.
Engine Air Cleaner/Filter
As you face the front of the vehicle, the engine air
cleaner is in the front right section of the engine
compartment. There is a filter inside the air cleaner.

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6-17
Supercharger Oil
Unless you are technically
qualified and have the
proper tools, you should let
your dealer or a qualified
service center perform this
maintenance.
When to Check
Check oil level every 30,000 miles (50 000 km) or every
36 months, whichever occurs first.
What Kind of Oil to Use
See ªRecommended Fluids and Lubricantsº in the Index
and use only the recommended oil.
How to Check and Add Oil
Check oil only when the engine is cold. Allow the
engine to cool two to three hours after running.
CAUTION:
If you remove the supercharger oil fill plug while
the engine is hot, pressure may cause hot oil to
blow out of the oil fill hole. You may be burned.
Do not remove the plug until the engine cools.
1. Clean the area around the oil fill plug before
removing it.
2. Remove the oil fill plug using a 3/16 inch
Allen wrench.
3. The oil level is correct when it just reaches the
bottom of the threads of the inspection hole.
4. Replace the oil plug with the O
-ring in place. Torque
to 88 lb
-in (10 N´m).

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6-18
Automatic Transaxle Fluid
When to Check and Change
A good time to check your automatic transaxle fluid
level is when the engine oil is changed.
Change both the fluid and filter every 50,000 miles
(83 000 km) if the vehicle is mainly driven under one or
more of these conditions:

In heavy city traffic where the outside temperature
regularly reaches 90F (32C) or higher.

In hilly or mountainous terrain.

When doing frequent trailer towing.

Uses such as found in taxi, police or delivery service.
If you do not use your vehicle under any of these
conditions, change the fluid and filter at 100,000 miles
(166 000 km).
See ªScheduled Maintenance Servicesº in the Index.
How to Check
Because this operation can be a little difficult, you may
choose to have this done at the dealership
service department.If you do it yourself, be sure to follow all the
instructions here, or you could get a false reading on
the dipstick.
NOTICE:
Too much or too little fluid can damage your
transaxle. Too much can mean that some of the
fluid could come out and fall on hot engine parts
or exhaust system parts, starting a fire. Be sure to
get an accurate reading if you check your
transaxle fluid.
Wait at least 30 minutes before checking the transaxle
fluid level if you have been driving:

When outside temperatures are above 90F (32C).

At high speed for quite a while.

In heavy traffic
-- especially in hot weather.

While pulling a trailer.
To get the right reading, the fluid should be at
normal operating temperature, which is 180F to
200F (82C to 93C).

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6-21
Thermostat
Engine coolant temperature is controlled by a thermostat
in the engine coolant system. The thermostat stops the
flow of coolant through the radiator until the coolant
reaches a preset temperature.
When you replace your thermostat, a GM thermostat i
s recommended.
Engine Coolant
The cooling system in your vehicle is filled with
DEX
-COOL
engine coolant. This coolant is designed
to remain in your vehicle for 5 years or 150,000 miles
(240 000 km), whichever occurs first, if you add only
DEX
-COOL
extended life coolant.
The following explains your cooling system and how to
add coolant when it is low. If you have a problem with
engine overheating, see ªEngine Overheatingº in
the Index.A 50/50 mixture of clean, drinkable water and
DEX
-COOL
coolant will:

Give freezing protection down to
-34F (-37C).

Give boiling protection up to 265F (129C).

Protect against rust and corrosion.

Help keep the proper engine temperature.

Let the warning lights and gages work as
they should.
NOTICE:
When adding coolant, it is important that you use
only DEX
-COOL (silicate-free) coolant.
If coolant other than DEX-COOL is added to the
system, premature engine, heater core or
radiator corrosion may result. In addition, the
engine coolant will require change sooner
-- at
30,000 miles (50 000 km) or 24 months,
whichever occurs first. Damage caused by the use
of coolant other than DEX
-COOL is not
covered by your new vehicle warranty.

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6-22 What to Use
Use a mixture of one-half clean, drinkable water and
one
-half DEX-COOL
coolant which won't damage
aluminum parts. If you use this coolant mixture, you
don't need to add anything else.
CAUTION:
Adding only plain water to your cooling system
can be dangerous. Plain water, or some other
liquid like alcohol, can boil before the proper
coolant mixture will. Your vehicle's coolant
warning system is set for the proper coolant
mixture. With plain water or the wrong mixture,
your engine could get too hot but you wouldn't
get the overheat warning. Your engine could
catch fire and you or others could be burned. Use
a 50/50 mixture of clean, drinkable water and
DEX
-COOL
coolant.
NOTICE:
If you use an improper coolant mixture, your
engine could overheat and be badly damaged.
The repair cost wouldn't be covered by your
warranty. Too much water in the mixture can
freeze and crack the engine, radiator, heater core
and other parts.
If you have to add coolant more than four times a year,
have your dealer check your cooling system.
NOTICE:
If you use the proper coolant, you don't have to
add extra inhibitors or additives which claim to
improve the system. These can be harmful.