Service Intervals
Versus Oil Change Periods (information from Castrol) |
Richard Oliver |
While both car engine and oil
technology advancements have resulted in dramatically increased service intervals
from 4000 to 10000 kilometres, Castrol observes a major problem which it
says is becoming increasingly apparent
Some car owners, it says, are
unknowingly imposing upon themselves a false sense of security by assuming
that their oil only needs to be changed in conjunction with their 10,000
or 15,000 kilometre mechanical service. Unfortunately, says the company,
they are in danger of damaging their engine, therefore minimising its
life.
Why? Because owners haven't
checked the section of their vehicle manual to identify personal driving
habits, and under what conditions the 10/15,000 kilometre oil change periods
do or do not apply. These conditions greatly affect the life of the engine
oil, and consequently the engine. In fact, today's engines generally last
about 200,000 kilometres, but if well looked after, can achieve as much as
500,000 kilometres without major overhauls.
Vehicle manufacturers are
designing their engines to take an SAE 1OW- 30 oil and in some instances,
even lighter. These reduce friction, help improve fuel consumption and assist
in the reduction of exhaust emissions, all very positive benefits if the
right driving conditions apply.
The trend to use these lower
viscosity oils is becoming more common, but like the heavier viscosity oils
such as 2OW-50, they still suffer from fuel dilution resulting in oil thinning.
The fuel enters the oil on cold start-up and depending upon the driving condition
of the vehicles, may or may not, get the opportunity to be vaporised
out.
Castrol says what most drivers
do not know is that water vapour, unburnt petrol and blow-by gases from the
combustion process overload the oil. These combine to produce sludge deposits.
It takes about 20 kilometres from a cold start to fully warm up the engine
oil and reduce the rate of fuel contaminations.
That does not effectively
take place in engines that do not travel further than 20 kilometres after
each cold start . The oil is soon saturated with contaminants and its protective
ability is destroyed, no matter what high quality grade it is
Consequently, oil thick with
deposits cannot reach the moving parts as quickly when the engine is first
started - the point at which most engine damage occurs. It is a less effective
lubricant, accelerating wear and leakage, especially now that many modern
engines have reduced sump capacities some as low as 3.5 litres, causing the
oil to be under lot more stress- particularly as it reaches the end of its
effective service life.
Castrol recommends that a
vehicle travelling less than 20 kilometres per trip for more than half of
its journeys should have an oil change every 5000 to 7000 kilometres. Most
manufacturers service schedules recommend oil changes every six months -
if a vehicle is driven a number of times in a week and does not reach the
maximum distance in that time, the oil should be changed. This affects about
80 % of vehicles that do little more than a token stop-start to work, to
the station, to school or to the shopping centre and are at risk of increased
engine wear and damage compared with a car which travels long enough
to vapourise the potentially damaging contaminants.
Other abnormal conditions
that should reduce oil change intervals include dusty roads, heavy loads,
and sustained high speeds. Also, simply topping up an engine low on
oil with new oil is not the same as giving it an oil change. Contaminants
left behind increase in concentration each time the oil level drops, accelerating
engine wear.
So, to protect your investment,
take the time to check the vehicles manual to identify what your driving
conditions are and how they affect the oil, even between regular service
periods, or simply inquire when you next have your car serviced. Correctly
followed, you will maximixe the life of your engine, help contribute to lower
pollution and save many thousands of dollars in the long run., |