Evening star., 1921-04-24
VITAL AIDS FOR MOTORISTS
IN CHOOSING OF PROPER OILS
'Speedometer' Method Branded as Un-
safe-Four Mistaken Ideas
Corrected.

rate of wear is very gradual and de-
pendent upon the degree to which the
engine is correctly and efficiently lu-
bricated; finally, the continued and
accumulating wear causes pounding
of the rings in their grooves and oil
consumption rapidly increases. Eek.
cessive wear should be cut short and
corrected mechanically by repairs OF
repla dement's of the worn parts.
Three More Factors.
Mistaken idea No. 3, that piston
clearances and piston ring fits alone
determine the choice of the proper
oil.
| While it is absolutely necessary that
the correct oil be one OF ample body
and proper character to seal the pis-
ton rings against gas leakage under
all operating conditions. there are
| three other equally important fac
tors which must be considered in Sc
| lecting the correct oil for any auto
| motive engine.
The first is the operating tempera-
ture. This is Influenced by the type
! OF service, the type of cooling SyS-
tenn employed. the cylinder dimen-
sions. valve arrangement and by the
| details of design.
| Second is the ability of the lubricat-
ing system to handle oils of different
/ bodies.
1t is well known that certain types
OF systems will lend themselves bet
ter to the distribution Of light bodied
! oils. while others work best with oils
of medium or heavy body. 1t is also
true that in some cases, due to de-
tails of the lubrcating system, the
employment Of heavy-bodied oils may
prove disastrous. due to lack of dis
tribution of the oil under some operat.
ing conditions.
The third factor is carbon deposit
| Due to characteristics Of design
some engines will not burn cleanIy
oils of heavy body. The result is
excessive carbon deposit, which does
not form when lighter oils are used
heavier oils are used to overcome
wear.
In other words. there are three
very important factors which. ir
addition to piston and piston ring
clearances, affect the selection of the
; correct oil and which may render in
advisable the use of oils of heavy
body.
| Mistaken idea No. 4-That the use
Of heavy-bodied oil in engines that
have worn excessively will overcome
oil pumping.
| Heavier Bodied Oils Used.
Oil pumping is the term usually
applied when an engine is using
large quantities of oil In many
ing and almost invariably in carbon
deposits.
When oil pumping occurs in cars
whlch nave previously worked sat
isfactorily heavier bodied oils are
| often employed to reduce it.
1t is fact that heavier-bodied oils
are usually consumed more slowly
than light-bodied oils, but this re-
mains true regardless Of the condi-
tion Of wear. Hence. II a change
engine this oil will also be consum ed
in proportionately excessive amounts
Consequently. when such oils work
into the combustion chambers in ex-
cessive amounts they are not com.
large quantities Of carbon.
Therefore, II the engine design
were such that = avy-bodied OF
could not be used when the engine
was in good condition. due to ex.
be still more unsatisfactory wher
wear permitted it to pass the pis.
tons in excess.
Any other factors Of design max
oil in a new car would continue tt
exist regardless OF wear and render
its use inadvisable.
| We ind that the determinatio1~o o.
suitable lubricants for automobile ol
motor truck engines on an arbitrar.
mileage basis is unsound because:
l. Rate Of wear is not constant
for all engines. 1t varies with the
design. material. manufacturing fin.
ish and the care given them in serv'
ice. It il chiefly controlled by the
value Of the lubricants used.
2. Wear is not measurable in terms
Of mileage operation. The initial
hnish Of the working parts is a factor
which varies widely. especially in
large quantity production; and all