Topics > Oil Temperature and Engine Life
Topic - Oil Temperature and Engine Life
is proper temperature so important?
vs. Oil Temperature
maintained 911 engines can last over 300,000 miles when oil
temperature is kept in the optimal 180°-210°F range. As oil
temperature rises engine life declines rapidly.
If the temperature is too high the engine will fail in short
order. But why?
explain this we need to look at what is happening at the surface of
the moving parts. Under microscopic examination, the machined
surfaces are not truly smooth but instead have minute peaks and
valleys. When two such surfaces are forced to slide over each other
opposing high spots will contact, resisting any sliding action. The
contact causes distortion, scuffing, micro-welding and subsequent
tearing. An engine operating like this will not last!
all the moving parts it seems impossible that an engine can last
300,000 miles, yet they do. The reason is that in normal
operation the moving metal parts do not actually contact each other!
the parts move relatively quickly and sufficient viscous oil is
present the oil is dragged between the surfaces filling the space
between. The surfaces "float" on the oil film and no
metallic contact occurs. This condition is called hydrodynamic
Viscosity is a measure of an oils ability to flow. The viscosity
controls the thickness of the oil film under hydrodynamic
lubrication. Oils lose viscosity with increasing temperature.
temperature increases and
viscosity drops the oil film layer gets progressively thinner.
Eventually, metal irregularities begin to contact and we no longer
have hydrodynamic lubrication. The condition becomes more pronounced
as temperature continues to climb and viscosity and film thickness
continue to decline. Engine wear increases dramatically.
you have it. When oil is the proper temperature the moving parts
operate in hydrodynamic lubrication, are not in contact and wear
very little. With rising temperature viscosity drops and
metal-to-metal contact begins. Engine wear is greatly
your car with an
oil cooler will help ensure
Moreland - February 2003
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