1997 TOYOTA TACOMA oil change

11 8FUNCTIONS OF ENGINE OIL
Engine oil has the primary functions of lubri-
cating 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 con-
sume 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 isleft 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 com-
bustion gases during the combustionprocess.
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 tem- perature exhaust gases also burn the
oil used to lubricate the exhaust valve stems.
The amount of engine oil consumed de-
pends on the viscosity of the oil, the
quality of the oil and the conditions the
vehicle is driven under.
More oil is consumed by high- speed driving
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 con-
sumption, note that the oil may become
diluted and make it difficult to judge the
true level accurately.
As an example, if a vehicle is used for re-
peated 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 be-
cause the oil is gradually becoming diluted
with the 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 itappear that oil is excessively consumed
after driving as 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 essen-
tial that the oil level be checked regularly.
Toyota recommends that the oil level bechecked every time you refuel the vehicle.
Failure to check the oil level
regularly could lead to serious
engine trouble due to insufficient oil.
NOTICE
For detailed information on the oil level
check, see Checking the engine oil levelº
in Chapter 7-2.
Facts about engine oil consumption

169
Tire surface and wheel nuts Check the tires carefully
for cuts, damage
or excessive wear. See Chapter 7-2 for
additional information. When checking the tires, make sure no nuts are missing,
and check the nuts for looseness. T ighten
them if necessary.
Tire rotation
Rotate the tires every 12000 km (7500
miles). See Chapter 7-2 for additional in- formation.
Fluid leaks Check underneath for leaking fuel, oil, wa-
ter or other fluid after the vehicle has been
parked for a while. If you smell fuel fumes
or notice any leak, have the cause found
and corrected immediately. Doors and engine hood Check that all doors including tailgate op- erate smoothly and all latches lock se-
curely. M ake sure the engine hood secon-
dary latch secures the hood from opening
when the primary latch is released. INSIDE THE VEHICLE Items listed below should be checked
regularly, e.g. while performing peri-
odic services, cleaning the vehicle,etc. Lights Make sure the headlights, stop lights, tail lights, turn signal lights, and other lights are all working. Check headlight aim. Service reminder indicators and
warn-
ing buzzers Check that all service reminder indicators
and warning buzzers function properly. Steering wheel
Be alert for changes in steering condition, such as hard steering or strange noise. Seats Check that all front seat controls such as
seat adjusters, seatback recliner, etc. op- erate smoothly and that all latches lock
securely in any position. Check that the
head restraints move up and down
smoothly and that the locks hold securely
in any latched position. For folding-down
seatback (bench seat), check that the
latches lock securely. Seat belts
Check that the seat belt system such as
buckles, retractors and anchors operate
properly
and smoothly. Make sure the belt
webbing is not cut, frayed, worn or dam-aged. Accelerator pedal Check the pedal for smooth operation and
uneven pedal effort or catching. Clutch pedal Check the pedal for smooth operation. Brake pedal Check the pedal for smooth operation and
that the pedal has the proper clearance. Check the brake booster function. Brakes
At a safe place, check that the brakes do not pull to one side when applied. Parking brake Check that the lever has the proper travel and that, on a safe incline, your vehicle is
held securely with only the parking brake applied.

170Automatic transmission Parkº
mech-
anism
Check the lock release button of the se-
lector lever for proper and smooth opera-
tion. On a safe incline, check that your ve-
hicle is held securely with the selector lever in ºPº position and all brakes re- leased.
IN THE ENGINE COMPARTMENT Items listed below should be checked
from time to time , e.g. each time when
refueling.
Washer fluid
Make sure there is sufficient fluid in the
tank. See Chapter 7-3 for additional infor-
mation.
Engine coolant level Make sure the coolant level is between
the FULLº and LOWº lines on the see-
through reservoir when the engine is cold.
See Chapter 7-2 for additional informa-tion.
Battery electrolyte level Make sure the electrolyte level of all bat-
tery cells is between upper and lower level
lines on the case. Add only distilled water
when replenishing. See Chapter 7-3 for
additional information. Brake fluid level
Make sure the brake fluid level is correct. See Chapter 7-2 for additional informa- tion.
Engine oil level
Check the l
evel on the dipstick with the en-
gine turned off and the vehicle parked on
a level spot. See Chapter 7-2 for addition-
al information. Power steering fluid level Check the level on the dipstick. The level
should be in the HOTº or COLDº range
depending on the fluid temperature. SeeChapter 7-2 for additional information. Exhaust system
If you notice any change in the sound of
the exhaust or smell exhaust fumes, have the cause located and corrected immedi-
ately. (See engine exhaust cautions in
Part 2.) Be on the alert for changes in perfor-
mance, sounds, and visual tip-offs
that in-
dicate service is needed. Some important
clues are as follows: Engine missing, stumbling, or pinging
Appreciable loss of power
Strange engine noises
A leak under the vehicle (however, wa-
ter dripping from the air conditioning
after use is normal.)
Change in exhaust sound (This may
indicate a dangerous carbon monox-
ide leak. Drive with the windows open
and have the exhaust system checked
immediately.)
Flat-looking tire; excessive tire squeal
when cornering; uneven tire wear
Vehicle pulls to one side when drivingstraight on a level road
Strange noises related to suspensionmovement
Loss of brake effectiveness; spongy
feeling brake or clutch pedal; pedal al-
most touches floor; vehicle pulls to one
side when braking
Engine coolant temperature continual-
ly higher than normal
Does your vehicle need repairing?