|Soiled plugs, tired engine
Question : MY Toyota Corolla 1300 is 16 years
old and has clocked 140,000km.
Over the past five years, the car is mainly driven just from my home to the LRT
station and back, a total of approximately
2km. I service the car at intervals of six
months since it hardly travels 2,000km in
At my last service, I have noticed that
my spark plugs were covered with oil and
soot. Please advise as to what the causes
might be, and whether the low mileage
and utilisation will affect the engine in the
MODERN engines have longer service lives
compared with the engines manufactured
in the 1960s and 1970s. The reasons are
better manufacturing technology and
materials, and also a marked improvement
in the quality of lubricants.
However, the actual life of the engine in
service depends on numerous factors, such
as regularity of service, the type of lubricant
used, the ambient temperatures under which
the engine is operated and the type of usage
the engine has been put through.
The presence of oil and soot on the spark
plugs does not normally bode well for your
engine. In most cases, it is a sign of extensive
The presence of engine oil or engine oil
deposits on the spark plugs mean that an
excessive amount of engine oil is entering
the combustion chamber, the oil is not burnt
off and is deposited as a heavy layer of soot
on the plugs.
This is usually accompanied by an
increase in oil consumption. Unfortunately,
when a situation like this arises, the only
solution is a complete engine overhaul, often
at a substantial cost.
A cheaper solution is to fit a used engine,
but there are risks since there is no way of
telling the condition of an engine that has,
been removed from the vehicle, save by
examining the spark plugs.
Short journeys will shorten the overall life
of your engine because the engine does not
get to warm up properly.
Cold running shortens engine life because
moisture from combustion condenses and
combines with residues to form acids which
are corrosive to engine components. Cold
running also means more fuel is required,
and the excess washes lubricants off the
Also, engine components do not reach
their optimum operating temperature where
they are able to operate smoothly.