"Anthony" > wrote in message
...
> >
> >
> A certian minute volume of oil is consumed each cycle due to the surface
> finish on the cylinder wall. It is designed that way. (Ring
> lubrication).

Depends on what you call "minute", many engines in good condition go 5000+
miles with no discernible consumption as gauged by the dipstick.

In high school auto shop I attained the Hasting Piston Rings "Doctor of
Motors" certificate (I know, big deal). The training taught that proper
cylinder/ring lubrication can be attained with no loss of the lubricant.

The phenomenon was illustrated by placing a hankerchief over a silver dollar
and placing a lit cigarette (gasp) on the hankerchief. Other than a brown
smudge, the hankerchief is not burned because the coin absorbs the heat;
same thing happens in the combustion chamber, the heat of combustion passes
through the microscopic film of oil without burning it away and is absorbed
by the mass of the cylinder wall.

If not for this phenomenon, the oil on the part of the cylinder wall exposed
to combustion heat would be burned away and there would be no lubrication
for the rings as the piston travels from BDC to TDC on the exhaust stroke;
ring life would be very short.