Fuel Type; Octane Rating; Gasolines Containing Detergent Additives - Lexus GS300 1998 Owner's Manual

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.
At a minimum, the gasoline you use should meet the
specifications of ASTM D4814 in the U.S.A. and CGSB
3.5–M93 in Canada.
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 rating

Select premium unleaded gasoline with an Octane Rating
of 91 (Research Octane Number 96) or higher for
optimum engine performance. However, if such premium
type cannot be obtained, you may temporarily use
unleaded gasoline with an Octane Rating as low as 87
(Research Octane Number 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.
ENGINE
367