
How to Add Fluid 
Refer to the  Maintenance  Schedule  to  determine what kind of transmission 
fluid 
to use.  See “Recommended  Fluids and Lubricants”  in  the Index. 
Add  fluid only after  checking the transmission fluid 
HOT. (A COLD  check 
is used 
only as  a reference.)  If the fluid level  is  low,  add only enough of the 
proper  fluid to bring the level  up 
to the HOT area for a hot  check.  It doesn’t 
take  much  fluid, generally  less than  a 
int. Don ’t overfill. We recommend 
you use only fluid labeled  DEXRON 
-111, because fluid with that label is 
made  especially  for  your  automatic  transmission.  Damage caused  by fluid 
other  than DEXRON@-I11  is  not  covered by your 
new vehicle  warranty. 
8 
0 After adding  fluid, recheck  the fluid level as described under “How  to 
Check.” 
0 When the correct  fluid level is obtained,  push the dipstick back in all 
the way; then  flip the handle down 
to lock the dipstick in place. 
Manual  Transmission  Fluid 
When to Check 
A good  time  to have it checked is when the engine  oil is changed.  However, 
the  fluid 
in your manual transmission doesn’t require  changing. 
How to Check 
Because this operation  can be  a little difficult, you may  choose to have  this. 
done  at your 
GM dealer  Service  Department. 
If you do it yourself,  be sure  to follow all the instructions  here,  or you  could 
get  a  false  reading. 
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. 
Check  the  fluid level only when your  engine is off, the vehicle  is parked on 
a level  place  and the transmission is cool enough for you to rest your fingers 
on the transmission  case. 
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Then, follow these  steps: 
1.  Remove  the  filler  plug. 
2.  Check  that  the  lubricant  level  is  up to  the  bottom  of the  filler  plug  hole. 
3. If the  fluid  level  is  good,  install  the  plug  and  be  sure  it  is  fully  seated. If 
the  fluid  level  is low, add  more  fluid  as  described  in  the  next  steps. 
How to Add Fluid 
Here’s how  to  add  fluid.  Refer  to  the  Maintenance  Schedule  to  determine 
what  kind  of fluid  to  use.  See  “Recommended  Fluids  and  Lubricants”  in  \
the 
Index. 
1. Remove  the  filler  plug. 
2. Add  fluid  at  the  filler  plug  hole.  Add only  enough  fluid  to  bring  the 
fluid  level  up to  the  bottom  of the  filler  plug  hole. 
3. Install  the  filler  plug.  Be sure  the  plug  is  fully  seated. 
Hydraulic  Clutch 
The  hydraulic  clutch  linkage  in  your vehicle  is  self-adjusting.  A  slight 
amount 
of play (1/4 inch  to  1/2  inch)  in  the  pedal  is  normal. 
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When to Check  and What to Use 
Refer to  the 
Maintenance  Schedule 
to determine how 
often 
you should 
check  the 
fluid level 
in your clutch master 
cylinder reservoir  and 
d for the  proper  fluid. 
See  “Owner  Checks and Services”  and “Recommended Fluids  and 
Lubricants” 
in the  Index. 
How to Check 
The  proper  fluid should  be added if the  level  does not reach  the bottom of 
the  diaphragm  when it’s in place in the reservoir.  See the instructions on the 
reservoir  cap. 
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 ”Scheduled  Maintenance Services’‘ in 
the Index. 
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. 
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What to Use 
Refer to the  Maintenance  Schedule  to determine  what kind of lubricant  to 
use.  See “Recommended  Fluids  and Lubricants” 
in the  Index. 
C3 (3500 H.D.) Trucks  Equipped  with  Dana  Rear Axle 
Additional rear  axle scheduled  maintenance  is required on 3500 H.D. 
models  equipped  with Dana  rear axles when they are driven under the 
following  conditions: 
0 Extreme  loading (at or near  GVWR)  or trailer  towing,  and: 
Operation  above 45  mph for extended  periods  of time 
Vehicles  used 
in any  of  these conditions  require the rear axle lubricant (SAE 
8OW-90 - GL-5) be changed  every 3 months or 3,000 miles, whichever 
comes  first. 
To reduce  required  maintenance, SAE 75W-140 synthetic gear lubricant 
may  be  used. With  the  use  of synthetic 
SAE 75W-140  lubricant, the fluid 
change intervals  may be  increased  to  30,000 miles. Before  using SAE 
75W-140, it is important  to drain and flush the axle  with clean mineral 
based  (non-synthetic)  axle lubricant.  Fluid capacity  is 4.12  qts.  (3.9L). 
Four-  Wheel  Drive 
Most  lubricant  checks in this section also apply to  four-wheel-drive 
vehicles.  However,  they have two additional  systems that  need lubrication. 
Transfer  Case 
When  to  Check  Lubricant 
Refer  to the Maintenance  Schedule  to determine  how often  to  check the 
lubricant.  See  “Periodic  Maintenance  Inspections” 
in the Index. 
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How to Check  Lubricant 
What  to Use 
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. 
Refer  to  the  Maintenance  Schedule  to  determine  what kind of lubricant  to 
use.  See  “Recommended  Fluids  and  Lubricants”  in the  Index. 
Front 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  “Scheduled  Maintenance  Services” 
in 
the Index. 
How  to Check  Lubricant 
If the  level  is  below  the  bottom of the  filler  plug  hole,  you’ll need to  add 
some  lubricant. 
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If the differential is at operating  temperature  (warm),  add enough  lubricant 
to  raise  the level  to the bottom 
of the  filler  plug hole. 
If  the  differential  is cold,  add enough  lubricant  to  raise  the level to 
1/2 inch 
( 12 mm) below  the  filler plug hole. 
What to Use 
Refer  to the  Maintenance  Schedule  to  determine  what kind of lubricant to 
use. See “Recommended  Fluids  and Lubricants” in the Index. 
Engine 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  “Engine 
Overheating” 
in the Index. 
The  proper  coolant  for  your  vehicle will: 
Give  freezing protection  down  to -34°F (-37°C). 
0 Give boiling  protection  up to 262°F  (128°C). 
Protect  against rust and corrosion. 
Help  keep  the proper  engine  temperature. 
Let the warning  gages work as they  should. 
What  to Use 
Use a mixture of one-half cleun water (preferably  distilled) and one-half 
antifreeze  that  meets “GM Specification  6038-M,” which won’t  damage 
aluminum parts. 
You can also use  a recycled  coolant  conforming to “GM 
Specification  6038-M.”  Use  GM Coolant  Supplement  (Sealer)  with a 
complete  coolant  flush and refill. If  you  use this  mixture.  you don’t  need to 
add  anything  else. 
A 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 mix  will.  Your  vehicle’s  coolant 
warning  system 
is set for  the  proper  coolant mix. With plain 
water  or the  wrong  mix,  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 mix  of clean 
water  and 
a proper  antifreeze. 
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What to Add 
Refer to the Maintenance  Schedule to determine what  kind of' tluid to use 
See  "Recommended  Fluids  and Lubricants" 
in the Index. 
NOTICE: 
When  adding  power  steering  fluid  or  making  a  complete  fluid 
change,  always  use  the  proper  fluid.  Failure  to  use 
the proper 
fluid  can  cause  leaks  and  damage  hoses  and  seals. 
Hydro-Boost  Brake  System  (Hydraulic Pump) 
The power  steering pump is also  used as the Hydro-boost pump. Refer to 
"Power  Steering  System'' 
in this  section  when checking fluid level or 
adding  fluid. 
Windshield  Washer  Fluid 
What to Use 
When you need  windshield  washer  fluid, be sure to read  the manuhcturer's 
instructions  before  use. 
If you will be operating  your  vehicle in an area 
where the temperature 
may fall below  freezing, use a fluid that has 
sufficient protection  against  freezing. 
To Add 
Open the cap labeled 
WASHER FLUID 
ONLY.  Add  washer 
fluid 
until the  tank  is 
full. 
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Windshield  Wiper Blade Inserts 
To replace the 
windshield wiper 
blade insert, lift 
the 
wiper arm and  rotate 
the blade  until 
it is 
facing  away from the 
windshield. 
Unlatch  the end 
of the insert  from the holding clips. Remove the insert  and 
slide 
a new  one in place.  Make  sure  the blade is secured  in the clips. 
Air  Conditioning 
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  dealership check it out as soon as 
possi  bleb 
The  air  conditioning  will 
not work when the temperature  is below 40°F 
(4°C). 
Fluid Leak  Check 
After the vehicle has  been  parked for a while, inspect  the surface  under the 
vehicle  for  water, oil, fuel 
or other  fluids.  Water dripping  from the air 
conditioning  system after it has  been  used  is normal. 
If you notice fuel leaks 
or  fumes,  the causes  should be found and corrected at  once. 
Lock Cylinders 
To be sure  your locks operate properly, they  must be lubricated.  Your 
vehicle’s maintenance  schedule  will tell you  how  often to lubricate  them. 
See  “Recommended Fluids  and Lubricants”  in the Index  for 
the proper 
lubricant to use. 
You  should 
not use penetrating  oils because they could  wash out the factory 
installed  lubricant and cause 
the lock to bind.  De-icers  which  contain 
alcohol  could  also 
wash away the lubricant, so be sure  to lubricate  the lock 
after  using 
a de-icer of this type. 
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