HOLDEN WH II 2002 Series Owner's Handbook Manual page 123

Every internal combustion engine uses a certain amount of oil, especially when running­
in. The engine is dependent on oil for lubricating critical areas, such as the cylinder walls,
pistons, rings and valve stems. These parts are all subjected to high friction loads, and
will prematurely wear out without a constant supply of engine oil. A thin film of oil is left
on the cylinder walls, some of which is carried into the combustion chamber and burnt
during the combustion process. This also applies to the film of oil on the valve stems
which is drawn into the combustion chamber and burnt.
There are several other factors that contribute to the rate of oil consumption in your
engine: the way in which the car is operated; the quality and grade of oil; the oil level;
the dilution of the oil; worn pistons, rings, valve stems and guides.
Operation of the car: High speed driving and heavy towing increases engine
temperature, which lowers oil viscosity, causing more oil to reach the combustion
chamber and get burnt away. The oil level should always be checked prior to towing or
a long trip.
Quality and grade of oil: Oil viscosity is a significant factor in oil consumption. If you
use an oil which is too "thin" (low viscosity) your oil consumption will increase. Use only
the recommended grades of oil.
Oil level: Maintaining a proper oil level is also an important factor in controlling oil
consumption. An over-full engine will splash oil onto the cylinder walls in quantities
greater than the piston rings can control. This excess oil is drawn into the combustion
chamber and burnt, or may result in aeration of oil in the sump causing damage to the
engine.
Dilution: Probably the most prevalent complaint of oil consumption comes from the
driver whose car is frequently driven on short trips where the engine often fails to reach
normal operating temperatures. The oil becomes diluted by fuel and moisture that
settles in the oil pan. This may raise the oil level creating a false reading on the oil level
dipstick. For example, in a car that has accumulated 1 ,500 km of short distance or
intermittent city operation and has consumed a normal amount of oil, the level may not
have dropped from the FULL mark, due to dilution. If this car is driven for some distance
at highway speeds on a warm day, the dilution elements evaporate lowering the oil level.
This sudden change in oil level can give the driver the impression that an excessive
amount of oil has been "lost" in the highway operation.
Measuring oil consumption: A simple economy test can be performed if the driver is
concerned by an apparent drop in the oil level.
Add sufficient oil to bring the level up to the "FULL" mark on the dipstick (avoid
overfilling). Take note of the odometer reading and check the oil periodically. When the
level reaches the "ADD" mark, carefully measure the amount of oil required to return
the level back to "FULL" and note the odometer reading. The amount of oil added for
the kilometres travelled over the duration of the test indicates the oil economy of the
engine. Remember to check the oil level at the start and finish of the test on level ground
and allow time for oil to drain down. Avoid minor top-ups (0.25 to 0.5 litres) when
measuring oil economy, as inaccuracies of oil quantity added, may cloud the result.
If, after taking into account the above factors, you are still concerned that your engine
has excessive oil consumption then you should discuss the situation with a Holden
Dealer. Remember that an engine's oil consumption should not be judged until it has
run at least 10,000 km.
ENGINE OIL CONSUMPTION
Chapter
7
WEEKLY CHECKS
7-5