2007 GMC YUKON XL DENALI maintenance

5. Inspect or replace the engine air cleaner/lter.
6. Reinstall the cover and tighten the screws.
7. Reset the air lter restriction indicator, if
the vehicle has one, by pressing the top button
on the indicator.
{CAUTION:
Operating the engine with the air
cleaner/lter off can cause you or others
to be burned. The air cleaner not only
cleans the air; it helps to stop ames if
the engine backres. If it is not there and
the engine backres, you could be
burned. Do not drive with it off, and be
careful working on the engine with the air
cleaner/lter off.
Automatic Transmission Fluid
When to Check and Change Automatic
Transmission Fluid
It is usually not necessary to check the
transmission uid level. A transmission uid leak
is the only reason for uid loss. If you suspect
a small leak, then use the following checking
procedures to check the uid level. However, if
there is a large leak, then it may be necessary to
have the vehicle towed to a dealership service
department and have it repaired before driving the
vehicle further.
Notice:Use of the incorrect automatic
transmission uid may damage your vehicle,
and the damages may not be covered by
your warranty. Always use the automatic
transmission uid listed inRecommended
Fluids and Lubricants on page 561.
Change the uid and lter at the intervals listed in
the Maintenance Schedule. SeeScheduled
Maintenance on page 551. Be sure to use the
transmission uid listed inRecommended Fluids
and Lubricants on page 561.
440

Engine Coolant
The cooling system in your vehicle is lled with
DEX-COOL®engine coolant. This coolant is
designed to remain in your vehicle for ve years or
150,000 miles (240 000 km), whichever occurs
rst, 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, seeEngine
Overheating on page 448.
A 50/50 mixture of clean, drinkable water and
DEX-COOL
®coolant will:
Give freezing protection down to
−34°F (−37°C).
Give boiling protection up to 265°F (129°C).
Protect against rust and corrosion.
Help keep the proper engine temperature.
Let the warning lights and gages work as
they should.Notice:Using coolant other than DEX-COOL
®
may cause premature engine, heater core,
or radiator corrosion. In addition, the engine
coolant may require changing sooner, at
the rst maintenance service after each
30,000 miles (50 000 km) or 24 months,
whichever occurs rst. Any repairs would not
be covered by your warranty. Always use
DEX-COOL
®(silicate-free) coolant in your
vehicle.
445

Brakes
Brake Fluid
Your brake master
cylinder reservoir is
lled with DOT-3 brake
uid. SeeEngine
Compartment Overview
on page 430for the
location of the reservoir.
There are only two reasons why the brake uid
level in the reservoir might go down. The rst
is that the brake uid goes down to an acceptable
level during normal brake lining wear. When
new linings are put in, the uid level goes back
up. The other reason is that uid is leaking out of
the brake system. If it is, you should have your
brake system xed, since a leak means that
sooner or later your brakes will not work well,
or will not work at all.So, it is not a good idea to top off your brake uid.
Adding brake uid will not correct a leak. If you
add uid when your linings are worn, then you will
have too much uid when you get new brake
linings. You should add or remove brake uid,
as necessary, only when work is done on
the brake hydraulic system.
{CAUTION:
If you have too much brake uid, it can spill
on the engine. The uid will burn if the
engine is hot enough. You or others could
be burned, and your vehicle could be
damaged. Add brake uid only when work
is done on the brake hydraulic system.
See “Checking Brake Fluid” in this section.
When the brake uid falls to a low level, the brake
warning light will come on. SeeBrake System
Warning Light on page 233.
Refer to the Maintenance Schedule to determine
when to check your brake uid. SeeScheduled
Maintenance on page 551.
459

Battery
Your vehicle has a maintenance free battery.
When it is time for a new battery, get one that has
the replacement number shown on the original
battery’s label. We recommend an ACDelco
®
replacement battery. SeeEngine Compartment
Overview on page 430for battery location.
Warning:Battery posts, terminals, and related
accessories contain lead and lead compounds,
chemicals known to the State of California
to cause cancer and reproductive harm.
Wash hands after handling.
Vehicle Storage
If you are not going to drive your vehicle for
25 days or more, remove the black, negative (−)
cable from the battery. This will help keep
your battery from running down.
{CAUTION:
Batteries have acid that can burn you and
gas that can explode. You can be badly
hurt if you are not careful. SeeJump
Starting on page 464for tips on working
around a battery without getting hurt.
463

To disconnect the jumper cables from both
vehicles do the following:
1. Disconnect the black negative (−) cable from
the vehicle that had the bad battery.
2. Disconnect the black negative (−) cable from
the vehicle with the good battery.
3. Disconnect the red positive (+) cable from the
vehicle with the good battery.
4. Disconnect the red positive (+) cable from the
other vehicle.
5. Return the remote positive (+) terminal cover,
if equipped, to its original position.
All-Wheel Drive
Be sure to perform the lubricant checks described
in this section. There are 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. SeeScheduled
Maintenance on page 551.
How to Check Lubricant
To get an accurate reading, the vehicle should be
on a level surface.
(A) Drain Plug (B) Filler Plug
469

If the level is below the bottom of the ller plug hole,
you’ll need to add some lubricant. Add enough
lubricant to raise the level to the bottom of the ller
plug hole. Use care not to overtighten the plug.
What to Use
Refer to the Maintenance Schedule to determine
what kind of lubricant to use. SeeRecommended
Fluids and Lubricants on page 561.
Rear Axle
When to Check Lubricant
It is not necessary to regularly check rear axle
uid unless you suspect there is a leak or you hear
an unusual noise. A uid loss could indicate a
problem. Have it inspected and repaired.All axle assemblies are lled by volume of uid
during production. They are not lled to reach
a certain level. When checking the uid level on
any axle, variations in the readings can be caused
by factory ll differences between the minimum
and the maximum uid volume. Also, if a vehicle
has just been driven before checking the uid
level, it may appear lower than normal because
uid has traveled out along the axle tubes and has
not drained back to the sump area. Therefore, a
reading taken ve minutes after the vehicle
has been driven will appear to have a lower uid
level than a vehicle that has been stationary
for an hour or two. Remember that the rear axle
assembly must be supported to get a true reading.
470

How to Check Lubricant
To get an accurate reading, the vehicle should be
on a level surface.
The proper level is from 0.04 inch to 0.75 inch
(1.0 mm to 19.0 mm) below the bottom of the ller
plug hole, located on the rear axle. Add only
enough uid to reach the proper level.
What to Use
Refer to the Maintenance Schedule to determine
what kind of lubricant to use. SeeRecommended
Fluids and Lubricants on page 561.
Front Axle
When to Check and Change Lubricant
It is not necessary to regularly check front axle
uid unless you suspect there is a leak or you hear
an unusual noise. A uid loss could indicate a
problem. Have it inspected and repaired.
471

How to Check Lubricant
To get an accurate reading, the vehicle should be
on a level surface.
A:Fill Plug
B:Drain PlugIf the level is below the bottom of the ller plug
hole, located on the front axle, you may need
to add some lubricant:
When the differential is cold, add enough
lubricant to raise the level from 0 (0 mm)
to 1/8 inch (3.2 mm) below the ller plug hole.
When the differential is at operating
temperature (warm), add enough lubricant
to raise the level to the bottom of the ller
plug hole.
What to Use
Refer to the Maintenance Schedule to determine
what kind of lubricant to use. SeeRecommended
Fluids and Lubricants on page 561.
472