catalytic converter lexus LS400 1994 Repair Manual Information / 1994 LS400: ENGINE

ENGINE
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FUEL
Fuel type
Your vehicle must use only unleaded gasoline.
To help prevent gas station mixups, your Lexus has a smaller
fuel tank opening. The special nozzle on pumps with unleaded
fuel will fit it, but the larger nozzle on pumps with leaded gas
will not.
NOTICE:
Do not use leaded gasoline. Use of leaded gasoline will
cause the three-way catalytic converter to lose its
effectiveness and the emission control system to
function improperly. Also, this can increase
maintenance costs.
Octane number
Select premium unleaded gasoline with a Research
Octane Number of 96 (Octane Rating 91) or higher for
optimum engine performance. However, if such premium
type cannot be obtained, you may temporarily use
unleaded gasoline with an octane number as low as 91.
Use of unleaded fuel with an octane number or rating lower
than stated above will cause persistent heavy knocking. If
severe, this will lead to engine damage.If your engine knocks ...
If you detect heavy knocking even when using the
recommended fuel, or if you hear steady knocking while
holding a steady speed on level roads, consult your Lexus
dealer.
However, now and then, you may notice light knocking for a
short time while accelerating or driving up hills. This is no
cause for concern.
Gasolines containing detergent additives
Lexus recommends use of gasolines that contain
detergent additives to avoid build-up of engine deposits.
For further details, ask your Lexus dealer or a local gasoline
retailer.
Gasolines containing MTBE
Gasolines that contain MTBE (Methyl Tertiary-Butyl Ether)
are available in the market. If you use a gasoline mixed
with MTBE, make certain that it does not contain more
than 15% of MTBE.
If the use of gasolines containing MTBE causes poor drivability
and / or poor fuel economy, you should discontinue the use of
fuels containing MTBE.