Chevrolet 2009 Express Owner's Manual page 331

CAUTION:
{
Never use oil or grease on bolts or nuts because
the nuts might come loose. The vehicle's wheel
could fall off, causing a crash.
8. Remove any rust or dirt
from the wheel bolts,
mounting surfaces
and spare wheel.
9. Put the wheel nuts
back on with the
rounded end of the
nuts toward the wheel.
Tighten each wheel
nut by hand until
the wheel is held
against the hub.
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