GMC 2001 Sonoma Owner's Manual page 270

To provide cleaner air, all gasolines in the United States
are now required to contain additives that will help
prevent deposits from forming in your engine and fuel
system, allowing your emission control system to
function properly. Therefore, you should not have
to add anything to the fuel. In addition, gasolines
containing oxygenates, such as ethers and ethanol, and
reformulated gasolines may be available in your area to
contribute to clean air. General Motors recommends that
you use these gasolines, particularly if they comply with
the specifications described earlier.
NOTICE:
Your vehicle was not designed for fuel that
contains methanol. Don't use it. It can corrode
metal parts in your fuel system and also damage
plastic and rubber parts. That damage wouldn't
be covered under your warranty.
Fuel E 85 (85% Ethanol)
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The 8th digit of your vehicle identification number
(VIN) shows the code letter for your engine. You will
find the VIN at the top left of your instrument panel.
See "Vehicle Identification Number" in the Index.
If you have the 2200 L4 (Code 5) engine, you may use
either regular unleaded gasoline or ethanol fuel up to
-
85% (E 85); also see "Fuel (Gasoline)" listed
previously. If you have the 4.3L V6 engine use only
regular gasoline.
Only vehicles with the 2200 L4 (Code 5) engine may
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use 85% ethanol fuel (E 85).
Most service stations will not have an 85% ethanol
-
fuel (E 85) pump available. Those stations that do
-
have E 85 should have a label indicating minimum
ethanol content. Do not use the fuel if the minimum
ethanol content is greater than 85%. Your vehicle
may not operate properly if the ethanol content is
greater than 85%.
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At a minimum, E 85 should meet
ASTM D 5798 specifications.
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