> I swear, it seems to me sometimes that oil actually soaks into metal.
Sometimes it does. Sintered bronze bushings, for example, are manufactured
in such a way that they have pores big enough to hold oil.
> Or
> maybe it's just that there is a thin film of oil on cylinder
> walls that never
> seems to go away. Every head I've pulled, if I run my finger on
> the cylinder
> wall, it "feels" lightly oiled.
I believe it's just a thin film. The film is actually very important, as
without it the rings and cylinder walls would rapidly wear. The rings have
to not actually touch the cylinder walls, but ride on the thin film of oil.
That's why TR motors have squirt holes in the rods to oil the walls, and
then oil control rings to scrape off the excess oil. (The squirt holes are
actually redundant, but that's why they are there.)
You can remove the film with soap and water ... the cylinder walls will
almost instantly start to rust ! So the film is also important to keep them
from rusting.
> Are oil molecules too big to squeeze into metal pores? Isn't
> this how cast
> iron frying pans are "seasoned" with oil?
Is there a tribologist in the house ? I don't think that's how it works, or
at least not all of it, but I really have no idea (contrary to popular
opinion it seems, I don't know everything <g>)
I would *guess* that the seasoning process creates a thin layer of black
iron (ferric) oxide on the surface on the pan (similar to the coating found
on some tools) and the coating is porous enough to hold some oil. But
that's just a WAG.
Randall
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