Adding Equipment To The Outside Of Your Vehicle; Fuel; Gasoline Octane - GMC YUKON XL 2004 Owner's Manual

CAUTION: (Continued)
•
Be sure to use the proper nuts, bolts and
other fasteners. "English" and "metric"
fasteners can be easily confused. If you
use the wrong fasteners, parts can later
break or fall off. You could be hurt.
Adding Equipment to the Outside of
Your Vehicle
Things you might add to the outside of your vehicle can
affect the airflow around it. This may cause wind
noise and affect windshield washer performance. Check
with your dealer before adding equipment to the
outside of your vehicle.
5-4

Fuel

Gasoline
The 8th digit of your vehicle identification number (VIN)
shows the code letter or number that identifies your
engine. You will find the VIN at the top left of the
instrument panel. See Vehicle Identification
Number (VIN) on page 5-112.
If your vehicle has the 5.3L V8 engine (VIN Code Z only),
you may use either regular unleaded gasoline or ethanol
fuel containing up to 85% ethanol (E-85); also see Fuel
E-85 (85% Ethanol) on page 5-6. In all other engines,
including the 5.3L V8 (VIN Code T), use only regular
unleaded gasoline.

Gasoline Octane

Use regular unleaded gasoline with a posted octane of 87
or higher. If the octane is less than 87, you may get a
heavy knocking noise when you drive. If this occurs, use
a gasoline rated at 87 octane or higher as soon as
possible. Otherwise, you might damage your engine. A
little pinging noise when you accelerate or drive uphill is
considered normal. This does not indicate a problem
exists or that a higher-octane fuel is necessary. If you are
using 87 octane or higher-octane fuel and hear heavy
knocking, your engine needs service.