GMC 2004 Yukon XL Owner's Manual page 472

CAUTION:
{
Rust or dirt on the wheel, or on the parts to
which it is fastened, can make the wheel nuts
become loose after a time. The wheel could
come off and cause an accident. When you
change a wheel, remove any rust or dirt from
the places where the wheel attaches to the
vehicle. In an emergency, you can use a cloth
or a paper towel to do this; but be sure to use
a scraper or wire brush later, if you need to, to
get all the rust or dirt off.
5-94
5. Remove any rust or dirt
from the wheel bolts,
mounting surfaces
and spare wheel.
CAUTION:
{
Never use oil or grease on studs or nuts. If you
do, the nuts might come loose. Your wheel
could fall off, causing a serious accident.
7. Turn the wheel wrench counterclockwise to lower
the vehicle. Lower the jack completely.
6. After mounting the
spare, put the wheel
nuts back on with the
rounded end of the nuts
toward the wheel.
Tighten each wheel nut
by hand. Then use the
wheel wrench to tighten
the nuts until the wheel
is held against the hub.