check oil GMC C-SERIES 1999 User Guide

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6-13
Engine Oil (Gasoline Engine)
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 located on the passenger's side
of the engine compartment.
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.
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.
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6-18
CAUTION:
Gasoline Engines Only: Operating the engine
with the air cleaner/filter off can cause you or
others to be burned. The air cleaner not only
cleans the air, it stops flame if the engine
backfires. If it isn't there, and the engine
backfires, you could be burned. Don't drive with
it off, and be careful working on the engine with
the air cleaner/filter off.
NOTICE:
Gasoline Engines Only: If the air cleaner/filter is
off, a backfire can cause a damaging engine fire.
And, dirt can easily get into your engine, which
will damage it. Always have the air cleaner/filter
in place when you're driving.
Your vehicle may also be equipped with an optional
Filterminder gage. See ªWarning Lights, Gages and
Indicatorsº in the Index.
Automatic Transmission Fluid
When to Check
A good time to have it checked is when the engine oil is
checked. See your Allison Automatic Transmission
Operator's Manual to find out when to change your
transmission fluid and filters.
How to Check and What to Use
The Allison Automatic Transmission Operator's Manual
that came with the vehicle shows how to check the
automatic transmission fluid and what fluid to use.
NOTICE:
Too much or too little fluid can damage your
transmission. 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
transmission fluid.
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6-19 Automatic Transmission External Filter
Your automatic transmission spin-on type filter requires
periodic replacement. It is mounted just behind the
radiator on the outside of the passenger's side frame rail.
Consult the Allison Automatic Transmission Operator's
Manual that came with the vehicle for proper
change intervals.
Automatic Transmission External Filter
With Service Trans Filter Indicator Light
(Option)
This automatic transmission spin-on type filter is
mounted to the left of the transmission. It requires
replacement when the SERVICE TRANS FILTER
indicator light on the instrument panel comes on or
every three years, whichever occurs first.
Manual Transmission Fluid
When to Check
A good time to have it checked is when the engine oil is
checked. See your Maintenance Schedule to find out
when to change your transmission fluid and filters.
How to Check and What to Use
The Eaton Fuller Transmission Operator's Manual that
came with the vehicle shows how to check the manual
tranmsmission fluid and what fluid to use.
NOTICE:
Too much or too little fluid can damage your
transmission. 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
transmission fluid.
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6-20
Rear Axle
When to Check and Change Lubricant
Refer to the Maintenance Schedule to determine how
often to check the lubricant and when to change it.
See ªScheduled Maintenance Servicesº in the
Maintenance Schedule.
How to Check Lubricant
If the level is below the bottom of the filler plug hole,
you'll need to add some lubricant. Add enough lubricant
to raise the level to the bottom of the filler plug hole.
What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. See ªRecommended Fluids and
Lubricantsº in the Maintenance Schedule.
Rear Axle Shift Motor (Option)
When to Check and Change Fluid
If you have an optional air-shift two-speed, controlled
traction, or locking differential type rear axle, a good
time to check the fluid level in the axle shift motor is
when the rear axle lubricant is checked. Use refrigerant
oil (shift motor only).
How to Check Fluid
Remove the plug on the front plate of the axle shift
motor, add enough fluid to raise the level to the bottom
of the filler plug hole, then replace the plug.
What to Use
Refer to your Maintenance Schedule to determine what
kind of lubricant to use.
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6-24 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.
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6-45 Fuel Filter (Diesel Engines)
The ACDelco
fuel filter is located in the component
box. See your Maintenance Schedule for recommended
service intervals.
Primary Fuel Filter and Water Separator
(Option)
If you have a Caterpillar

diesel engine, you may
have this spin
-on filter.
It is in the component box
on the driver's side behind
the fender.
It has a clear plastic drain bowl at the bottom. Check the
drain bowl occasionally for any water or particles. To
drain the bowl, shut off the engine. Then partially open
the drain valve at the bottom of the filter. See ªEngine
Oilº in the Index for proper disposal procedures.
Secondary Fuel Filter and Water
Separator/Heater (Option)
If you have a Caterpillar

diesel engine, you may have
this spin
-on filter and fuel
separator/heater. It is
mounted on the passenger's
side of the engine.
It has a metal drain bowl at the bottom. Occasionally, check
the bowl for any water or particles. To check or drain the
bowl, shut off the engine. Then push up on the spring loaded
drain valve until clear fuel is flowing from the valve. The
particles or water will drain out first. See ªEngine Oilº in the
Index for proper disposal procedures.
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6-46 Automatic Ether Injection System (Option)
If your diesel engine vehicle
has this feature, the ether
cylinder is on the upper
right rear side of the engine
compartment.
To change an empty ether cylinder, follow these steps.
1. Loosen the 5/16 inch screw head on the
cylinder
-to-bracket clamp.
2. Spread the clamp apart.3. Clean any dirt from the neck of the cylinder and the
top of the valve before you take out the cylinder.
4. Check the inside of the valve for any foreign matter.
Clean the valve as necessary.
5. Cover the valve to protect it from dirt and take out
the cylinder.
6. Install a new gasket whenever you take out the
cylinder. Use only one gasket and spread a light film
of clean oil on it before installation.
7. Put in the new cylinder. Turn it clockwise until it just
starts to contact the gasket.
8. Tighten the cylinder another half turn (180 degrees).
Don't over
-tighten.
9. Retighten the cylinder clamp.
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6-47 Front Wheel Bearings with Oil-Filled Hubs
If your vehicle has oil-filled
hubs, occasionally check to
see if they have enough oil.
You can tell by looking into
the sight glass to see if there
is oil there.
If there isn't, clean the rubber fill plug in the center of
the glass, and then remove it. Be careful not to allow
any dirt or water to get into the oil. Add enough of the
recommended oil to bring it up to the level mark that
you'll see on the glass.
Refer to your Maintenance Schedule for the proper oil
to use.
When you fill the hub, check the glass again after
driving a short distance. It takes a while for the oil to
flow through the system, and you may find that you
have to add a little more to fill it to the proper level.
Air Conditioning System
Every now and then, have your dealership check your
air conditioning system to be sure it has not lost any
cooling ability. If you think the system is not working
properly, have your GM Truck dealer check it out as
soon as possible.
The air conditioning won't work when the temperature
outside is below 40
F (4
C).
NOTICE:
If your vehicle is equipped with factory air
conditioning, the system is charged with the
R
-134a refrigerant. Servicing of the air
conditioning system should be performed by a
trained service technician.
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6-75
Extending the recommended oil change interval requires
the use of an infrared oil analysis program which shows
the condition of the oil and its additives. For more
information, consult your GM Truck dealer, who is an
authorized Caterpillar

engine dealer.
Transmission Capacity
Capacities (volumes) shown are approximate. For
manual transmissions, the correct oil level is to the
bottom of the fluid fill plug opening. The oil capacity
will vary, due to the angle of the transmission, with the
vehicle. For automatic transmissions, see the Allison
Automatic Transmission Operator's Manual for oil
check and maintenance information.
Manual Transmission Pints (Liters)
RT6609 12.0 (5.7). . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RT6610 12.0 (5.8). . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RTO6610 12.0 (5.8). . . . . . . . . . . . . . . . . . . . . . . . . . . RT6613 16.0 (7.5). . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RT7608LL 19.5 (9.3). . . . . . . . . . . . . . . . . . . . . . . . . .
RT8609 15.0 (7.0). . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FS4205A, FS4205B, FS4205C 12.5 (5.9). . . . . . . . . .
5205A, FS5205C 12.5 (5.9). . . . . . . . . . . . . . . . . . . . .
FS5306 18.0 (8.5). . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FS6305A, FS6305B 19.0 (9.0). . . . . . . . . . . . . . . . . . .
FS6306 19.5 (9.2). . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FS7206 20.0 (9.5). . . . . . . . . . . . . . . . . . . . . . . . . . . . .
T8607B 36.0 (17.0). . . . . . . . . . . . . . . . . . . . . . . . . . .
Automatic Transmission Pints (Liters)
AT542 (for oil pan filter change) 30.0 (14.0)*. . . . . . .
AT545 (for oil pan filter change) 40.0 (19.0)*. . . . . . .
MT643 (for oil pan filter change) 13.0 (24.5)*. . . . . .
MT653 (for oil pan filter change) 36.0 (17.0)*. . . . . .
*Add two pints (one liter) when changing spin
-on filter.
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7-5
Scheduled Maintenance
The services shown in this schedule up to 100,000 miles
(166 000 km) should be performed after 100,000 miles
(166 000 km) at the same intervals. The services shown
after 100,000 miles (166 000 km) should be performed
at those same intervals.
This vehicle has a computer that lets you know when to
change your engine oil. This is not based on mileage,
but on engine revolutions and engine operating
temperature. When the computer has calculated that the
oil needs changing, the Oil Life Indicator will indicate
that a change is necessary.
See ªFootnotesº at the end of this Maintenance Schedule
for further explanation of maintenance services and
Caterpillar

diesel application.
100 Miles (160 km)
Wheel stud nut service. (45)
500 Miles (800 km)
Wheel stud nut service. (45)
1,000 Miles (1 600 km)
Wheel stud nut service. (45)(46)
3,000 Miles (5 000 km)
Engine oil and filter service. (3)(9)
Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
Clutch pedal free travel service. (10)
Rear axle air shift motor service. (11)
6,000 Miles (10 000 km)
Engine oil and filter service. (3)(9)
Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
Chassis lubrication service (or every 6 months,
whichever occurs first). (12)
Lubricate door hinge pins and rollers with engine oil.
Wheels and tires service. (15)
Hydraulic brake service (or every 6 months,
whichever occurs first). (7)
Hydraulic parking brake service (or every 6 months,
whichever occurs first). (8)
Clutch pedal free travel service. (10)
9,000 Miles (15 000 km)
Engine oil and filter service. (3)(9)
Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
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