, 1918-08-22
INFERIOR OIL IS
MOST EXPENSIVE
Low-Grade Lubricant Fouls
Spark Plugs, Breeds Carbon
and Other Trouble.
LITTLE POWER IS DEVELOPED
Among Other Annoyances From Car
bon Collection Is Knock In Engine
Raising Compression to Point
Where PreignItIon Occurs.

Have you a surplus of carbon about
your car-especially in the cylinders?
Does 1t clog up the combustion cham
Der, stick on the valves and make
them leak, and issue in black smoke
from the exhaust, to the accompani-
ment of sundry knocks? Better con-
serve your carbon and burn it all, for
there Is a carbon Hoover in sight and
he may cut down on your rations-of
oil and gasoline.
Owing to the high price and the
difficulty Of getting supplies of good
oil, poor grades are substituted right
along. In one case which came to my
attention an owner was having trouble
with the car, says a writer in an ex-
change. There was knocking and the
spark plugs fouled, causing irregular
running of the engine. The owner had
been using a high-grade oil. He could
not get his particular brand and
bought another at the same price, sup
posing the quality to be the same be-
cause the price was. When his trouble
was studied 1t was found that, al
though he paid the same as for high
grade oil, he got a much inferior grade.
He was advised to change, did, and his
trouble ended. To get the good grades
now 1t is necessary to pay a consider
ably higher price than a year ago.
Will Not Stand Heat.
Some grades of oil will not stand
the intense heat Of the combustion
chamber, nor even the temperature of
the cylinder walls and piston. The
oil burns and forms carbon. This car
bon collects on the insulator Of the
spark plug and forms a path for the
ignition current over the insulator,
called a short circuit. This causes mis-
firing and the engine runs very jerky
and is altogether unsatisfactory.
This fault can be corrected easily
by cleaning the spark plug, but often,
with a poor grade of oil, 1t is neces-
sary to do the cleaning every 80 or
100 miles.
Carbon also collects on the seat Of
the exhaust valve, making it impos-
sible for the valve to close entirely,
with a consequent loss of gas on the
compression stroke. The effect of this
is that very little or no power is de-
veloped in the cylinder, and also mis-
firing and irregular running, the same
as with the short-circuited spark plug.
In some cases this can be corrected
easily by taking out the valve cap and
disconnecting the valve spring, when
the valve may be removed and the car
bon scraped from valve and seat with
a knife or other instrument. Then a
slight grinding in of the valve will
give a tight joint.
Knock In Engine.
Another annoyance which comes
from carbon accumulation is a knock
in the engine, which results from the
decrease In the size of the combustion
chamber in proportion to the accumu-
lation. This raises the compression to
a point where preignition occurs
Hence the knock. To overcome this
trouble 1t is necessary to remove the
cylinders from the crank case and
have the carbon scraped out. Where
the cylinder head Is removable that OBJ
viates the necessity Of removing the
cylinders.
Temporary relief may be had by
having the carbon burned out by the
oxygen process. Liquid carbon remov-
ers help out, but are not so good, be-
cause the carbon which is loosened
goes to the muffier, where 1t is likely
to clog the small holes and materially
decrease the power of the engine by
preventing a free exhaust.
While 1t is possible to overcome
these troubles. it is much better to
buy a good grade of oil in the begin
ming and prevent them.