GMC 2003 Envoy - Manual (Page 300)

Fuel
Use of ihe recommended fuel is an Importan! part of ihe
proper maintenance of your vehicla.
Gasoline Octane
Use regular unlgacied gasoline with a posted ocfane
ot &7 or higher. If ihe octane is less ihan 87,, you may
get a heavy knocking noise when you drive, if ihts
occurs, use
a gasoline rated al &7 octane or higher as
soon as possible. Otlienwise, you might damage
your engine, A iittle plngirig noise when you accelerate
or drive uphill is considered normals This doas not
indicate a problem etifsts or that a higher-octane fuel is
necessary. If you are using 37 octane or higher-octane
fuel and hear heavy knocking, your engine needs
service*
Gasoiine Specifications
It Ls recomimended that gasoline meet specifications
whicfi were developed by the American Aulomobile
Manutacturem Association and endorsed by the
Canadian Vehicle Manufacturers Association tor better
vehicle perforrnance and engine proteclion. Gasoline
meeijng ihese specifications could provide improved
dnveahilily and emission coni rol system performance
cornpared to oiher gasoline.
In Canada, look for the
■'Aulo Makers’ Choice"
label on Ihe pump.
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