
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.