GMC 2013 Sierra Denali Owner's Manual page 288

At a minimum, E85 should meet
ASTM Specification D 5798 or
CGSB Specification 3.512. Filling
the tank with fuel mixtures that do
not meet ASTM or CGSB
specifications can affect driveability
and could cause the malfunction
indicator lamp to come on. As the
outside temperature approaches
freezing, ethanol fuel distributors
should supply winter grade ethanol,
the same as with unleaded
gasoline.
It is best not to alternate repeatedly
between gasoline and E85. If you
do switch fuels, it is recommended
that you add as much fuel as
possible do not add less than
11 L (3 gal) when refueling. You
should drive the vehicle immediately
after refueling for at least 11 km
(7 mi) to allow the vehicle to adapt
to the change in ethanol
concentration.
E85 has less energy per liter
(gallon) than gasoline, so you will
need to refill the fuel tank more
often when using E85 than when
you are using gasoline. See
.
If the vehicle has a diesel engine,
see the Duramax diesel supplement
for more information.
Fuel vapors and fuel fires burn
violently and can cause injury or
death.
To help avoid injuries to you
and others, read and follow
all the instructions on the fuel
pump island.
Turn off the engine when
refueling.
Keep sparks, flames, and
smoking materials away
from fuel.
Do not leave the fuel pump
unattended.
Do not reenter the vehicle
while pumping fuel.
Keep children away from the
fuel pump and never let
children pump fuel.
(Continued)