octane Lexus GS350 2008 Do-it-yourself maintenance / LEXUS 2008 GS460/350 OWNER'S MANUAL (OM30A87U)

71
1-5. Refueling
1
Before driving
GS_G_U
May 13, 2008 5:14 pm
Closing the fuel tank capAfter refueling, turn the fuel tank
cap clockwise until you hear a
click. The cap will revolve slightly in
the opposite direction once
released.
■Fuel types
Use premium unleaded gasoline. (91 Octane Rating [Research Octane Number
96] or higher)
■Fuel tank capacity
Approximately 18.7 gal. (71 L, 15.6 lmp.gal.)
■When the fuel filler door opener switch is inoperable
The lever can be used to open the fuel filler
door if the fuel filler door cannot be opened
using the inside switch because the 12 volt
battery is discharged or for any other reason.

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6-1. Specifications
6
Vehicle specifications
GS_G_U
May 13, 2008 5:14 pm
Engine
Fuel
GS460GS350
Model1UR-FSE2GR-FSE
Ty p e8-cylinder V type,
4-cycle, gasoline6-cylinder V type,
4-cycle, gasoline
Bore and stroke3.70  3.27 in. (94.0  83.0 mm)
Displacement281.2 cu.in. (4608 cm3)210.9 cu.in. (3456 cm3)
Drive belt tensionAutomatic adjustment
Fuel typePremium unleaded gasoline only
Octane Rating91 (Research Octane Number 96) or higher
Fuel tank capacity18.7 gal. (71 L, 15.6 Imp.gal.)

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6-1. Specifications
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Vehicle specifications
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May 13, 2008 5:14 pm
Fuel information
■Fuel tank opening for unleaded gasoline
To help prevent incorrect fueling, your Lexus has a fuel tank opening that only
accommodates the special nozzle on unleaded fuel pumps.
■If premium gasoline is not available
If 91 Octane cannot be obtained, you may use unleaded gasoline with an Octane
Rating as low as 87 (Research Octane Number 91). 
However, use of unleaded fuel with an Octane Rating lower than 91 may result in
engine knocking or drastically reduce output to protect itself while driving with a
heavy load. Persistent knocking can lead to engine damage and should be cor-
rected by refueling with higher octane unleaded gasoline.
■If your engine knocks
●Consult your Lexus dealer.
●You may occasionally notice light knocking for a short time while accelerating
or driving uphill. This is normal and there is no need for concern.
■Gasoline quality
In very few cases, driveability problems may be caused by the brand of gasoline you
are using. If driveability problems persist, try changing the brand of gasoline. If this
does not correct the problem, consult your Lexus dealer.
Your vehicle must use on ly unleaded gasoline.
Premium unleaded gasoline with an Octane Rating 91 (Research Octane
Number 96) or higher required for optimum engine performance.
At minimum, the gasoline you use should meet the specifications of
ASTM D4814 in the U.S.A. an d CGSB3.5-M93 in Canada.

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6-1. Specifications
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May 13, 2008 5:14 pm
■Gasoline quality standards
●Automotive manufacturers in the US, Europe and Japan have developed a
specification for fuel quality called World-Wide Fuel Charter (WWFC) that is
expected to be applied worldwide.
●The WWFC consists of four categories that are based on required emission
levels. In the US, category 4 has been adopted.
●The WWFC improves air quality by lowering emissions in vehicle fleets, and
customer satisfaction th rough better performance.
■Lexus recommends the use of gasoline containing detergent additives
●Lexus recommends the use of gasoline that contains detergent additives to
avoid build-up of engine deposits.
●All gasoline sold in the US contains de tergent additives to clean and/or keep
clean intake systems.
■Lexus recommends the use of cleaner burning gasoline
Cleaner burning gasoline, including reform ulated gasoline that contains oxygen-
ates such as ethanol or MTBE (Methyl Tert iary Butyl Ether) is available in many
areas.
Lexus recommends the use of cleaner burning gasoline and appropriately blended
reformulated gasoline. These types of gasoline provide excellent vehicle perfor-
mance, reduce vehicle emissions and improve air quality.
■Lexus does not recommend blended gasoline
●Lexus allows the use of oxygenate blended gasoline where the oxygenate con-
tent is up to 10% ethanol or 15% MTBE.
●If you use gasohol in your Lexus, be sure that it has an octane rating no lower
than 87.
●Lexus DOES NOT recommend the use of gasoline containing methanol.

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6-1. Specifications
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Vehicle specifications
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■Lexus does not recommend gasoline containing MMT
Some gasoline contains octane enhancin g additive called MMT (Methylcy clopen-
tadienyl Manganese Tricarbonyl).
Lexus DOES NOT recommend the use of gasoline that contains MMT. If fuel con-
taining MMT is used, your emission control system may be adversely affected.
The malfunction indicator lamp on the inst rument cluster may come on. If this hap-
pens, contact your Lexus dealer for service.
NOTICE
■Notice on gasoline quality
●Do not use leaded gasoline. 
Leaded gasoline can cause damage to your vehicle’s three-way catalytic convert-
ers causing the emission control system to malfunction.
●Do not use gasohol other than that stated here. 
Other gasohol may cause fuel system damage or vehicle performance problems.
●Using unleaded gasoline with an octane number or rating lower than that stated
here will cause persistent heavy knocking. 
At worst, this will lead to engine damage.
■Fuel-related poor driveability
If after using a different type of fuel, poor driveability is encountered (poor hot start-
ing, vaporization, engine knoc king, etc.), discontinue the use of that type of fuel.
■When refueling with gasohole
Take care not to spill gasohol. It can damage your vehicle’s paint.