Using
the correct type and grade of oil is becoming more
important than it was in the past, because modern
engines are now revving to six or seven thousand r/min,
and are developing a lot more power per litre than
was the case 10 years ago. On a new car the oil recommended
in the owner's manual should be used, but such is
the pace of oil development that, on a car more than
six or seven years old, the help-line of any one of
the well-known oil companies should
be consulted.
A
modern oil is actually a soup consisting of a base
oil and a number of additives, each chosen not only
for the specific qualities it adds to the oil, but
also for its compatibility with the base and all the
other additives.
The
major additives are:
1.
Detergents, which improve engine cleanliness by preventing
deposit-forming gums and residues from settling out,
but keep them in suspension, so that the filter can
remove them.
2.
Dispersants, which control cold-sludging and carry
finely divided combustion products in suspension in
the oil, where the filter or an
oil-change removes them from the engine.
3.
Oxidation and corrosion inhibitors that reduce the
rate of oxidation, one of the most important causes
of oil deterioration.
4.
Anti-wear agents, to protect rubbing components against
wear.
5.
Oiliness agents, which help to decrease frictional
coefficients.
6.
Anti-foaming agents, because the crankshaft whips
the oil like an egg-beater.
7.
Pour depressants that lower the solidification temperatures.
8.
Viscosity-index improvers to increase the viscosity
of the base oil.
9.
Extreme-pressure agents to prevent scoring and seizing.
10.
Seal-swell agents, which help the oil seals to function
efficiently.
11.
Metal
de-activators, which retard catalytic oil activation.
This
mixture is carefully blended in
the right proportions to perform as
demanded by the engine manufacturers.
 There
are many oil additives on the market, but adding them
to your oil might disturb the above mix, and we don't
know of any that are approved by the engine manufacturers,
or by the oil companies for mixing with their regular
products, therefore we advise caution. Check
that the API code and SAE viscosity index match the
recommendations for your engine.
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