1999 Lexus GS300 Engine

ENGINE
386± ELECTRICAL SYSTEM
Battery ± Maintenance type battery
Specific gravity reading at 20C (68F):
Charging rates Quick charge
Slow charge
± Non±maintenance battery
Open voltage at 20C (68F):
Charging rates
1.260 Fully charged
1.160 Half charged
1.060 Discharged
15A max.
5A max.
12.7V Fully charged
12.3V Half charged
11.9V Discharged
[Voltage that is checked 20 minutes after the key is
removed with all the lights turned off]
5A max.

ENGINE
387
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.
Improved gasolines
The American Automobile Manufacturers
Association (AAMA) has developed a specification
of improved gasolines. The AAMA specification
offers optimal fuel information for better vehicle
performance and better protection of your engine.
Lexus recommends the use of gasolines that meet the
AAMA specification, if available, for improved drivability

ENGINE
388and emission control system.
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.
Gasolines containing MMT
Some gasolines contain an octane±enhancing
additive called MMT (methylcyclopentadienyl
manganese tricarbonyl).
Lexus does not recommend the use of gasolines that
contain MMT. If fuels containing MMT are used, your
emission control system may be adversely affected.
The Malfunction Indicator Lamp on the instrument
cluster may come on. If this happens, contact your
Lexus dealer for service.
Gasolines containing alcohol
Gasohol is a mixture of gasoline and ethanol. If you
use gasohol in your Lexus, be sure that it is
unleaded, has an octane rating no lower than 87 and
does not contain more than 10% ethanol. Lexus
does not recommend the use of gasolines
containing methanol.
If you use gasoline containing methanol, use only
gasoline meeting the requirements above and also
containing less than 5% methanol with cosolvents and
corrosion inhibitors for methanol.

ENGINE
389
Gasolines quality
In a very few cases, you may experience driveability
problems caused by the particular gasoline that you are
using. If you continue to have unacceptable driveability,
try changing gasoline brands. If that does not rectify
your problem, then consult your Lexus dealer.
NOTICE
Do not use gasohol other than stated above. It
will cause fuel system damage or vehicle
performance problems.
If drivability problems are encountered (poor
hot starting, vaporizing, engine knock, etc.),
discontinue its use.
Take care not to spill gasohol during refueling.
Gasohol may cause paint damage.
Fuel tank capacity
75 L (19.8 gal., 16.5 lmp.gal.)
FACTS ABOUT ENGINE OIL
CONSUMPTION
Functions of engine oil
Engine oil has the primary function of lubricating and
cooling the inside of the engine, and plays a major role
in maintaining the engine in proper working order.
Engine oil consumption
It is normal that an engine should consume some
engine oil during normal engine operation. The
causes of oil consumption in a normal engine are as
follows.
Oil is used to lubricate pistons, piston rings and
cylinders. A thin film of oil is left on the cylinder wall
when a piston moves downwards in the cylinder.
High negative pressure generated when the vehicle
is decelerating sucks some of this oil into the
combustion chamber. This oil as well as some part of
the oil film left on the cylinder wall is burned by the
high temperature combustion gases during the
combustion process.
Oil is also used to lubricate the stems of the intake
valves. Some of this oil is sucked into the combustion
chamber together with the intake air and is burned
along with the fuel. High temperature exhaust gases
also burn the oil used to lubricate the exhaust valve
stems.

ENGINE
390The amount of engine oil consumed depends on the
viscosity of the oil, the quality of the oil and the way
the vehicle is driven.
More oil is consumed under driving conditions such as
high speeds and frequent acceleration and
deceleration.
A new engine consumes more oil, since its pistons,
piston rings and cylinder walls have not become
conditioned.
When judging the amount of oil consumption, keep
in mind that the oil may have become diluted,
making it difficult to judge the true level accurately.
For example, if a vehicle is used for repeated short trips
and consumes a normal amount of oil, the dipstick may
not show any drop in the oil level at all, even after 1000
km (600 miles) or more. This is because the oil is
gradually becoming diluted with fuel or moisture, making
it appear that the oil level has not changed.
The diluting ingredients evaporate out when the vehicle
is then driven at high speeds, as on an expressway,
making it appear that oil is excessively consumed after
driving at high speeds.
Importance of engine oil level check
One of the most important points in proper vehicle
maintenance is to keep the engine oil at the optimum
level so that oil function will not be impaired. Therefore,
it is essential that the oil level be checked regularly.
Lexus recommends that the oil level be checked every
time you refuel the vehicle.
NOTICE
Failure to check the oil level regularly could lead
to serious engine trouble due to insufficient oil.
For detailed information on oil level check, see
ºChecking the engine oil levelº on page 392.

ENGINE
391
USED ENGINE OIL
CAUTION
Used engine oil contains potentially harmful
contaminants which may cause skin disorders such
as inflammation or skin cancer, so care should be
taken to avoid prolonged and repeated contact with
it. To remove used engine oil from your skin, wash
thoroughly with soap and water.
Do not leave used oil within the reach of children.
Dispose of used oil and used oil filters only in a safe
and acceptable manner. Do not dispose of used oil
and used oil filters in household trash, in sewers or
onto the ground. Call your Lexus dealer or a service
station for information concerning recycling or
disposal.

ENGINE
392
CHECKING THE ENGINE OIL
LEVEL
62G005a

GS400
GS300
With the engine at operating temperature and turned
off, check the oil level on the dipstick.
1. To get a true reading, the vehicle should be on a level
spot. After turning off the engine, wait a few minutes for
the oil to drain back into the bottom of the engine.
2. Pull out the dipstick, and wipe it clean with a rag.
3. Reinsert the dipstick and push it in as far as it will go,
or the reading will not be correct.

ENGINE
393
62G006±1
1Add oil 2O.K. 3Too full
4. Pull the dipstick out and look at the oil level on the end.
If it is between the full level mark ( 5
) and the low level
mark ( 4
), it is O.K.