In previous threads on this topic the chemically inclined answered that PTFE
breaks down at high temperatures to form highly corrosive acids which then
damage the metal it is supposed to protect.  So, while there is a noticeable
benefit at first, there is a terrible end result.  The breakdown temp is
somewhere around 400 degrees Fahrenheit I think.  While the oil is not at that
temperature all the time the cylinder walls are often hotter and the PTFE is
being applied to them and washed off again with every stroke of the piston.
The corrosive by-products build up in the oil and damage everything it touches.

Search the archives if you want to know more, that's all I remember.

Miguel

Andrew Grebneff wrote:
>
> If your transmission is
> >wining on acceleration, it has either a scorched bearing, or a scorched
> >gear, or many of both.
>
> A worn differential may also whine under load.
>
> My 095 trans suffered a collapsed mainshaft bearing; this did not quite
> make what you'd call a whine, but made a lower-pitched moan.
>
> Regarding teflon (PTFE), this is a plastic which has the lowest coefficient
> of friction known to man, I believe, and is also extremely resistant to
> heat (witness its use in Dupont coatings on nonstick frypans etc). But it
> is not all that hard, a bit like nylon. Surely, when minute particles of
> teflon are introduced to restricted spaces and squeezed between metal
> surfaces at high pressures (eg within bearings, between piston and cylinder
> wall etc), some of this material would be rubbed into the surface
> irregularities in the metal? This SHOULD produce something of an incomplete
> and very slippery coating, though this wouls eventually wear away. Whether
> such a coating would be capable of giving a measurable, much less
> noticable, improvement in performance or fuel-efficiency is doubtful. But I
> cannot see how it should be able to cause harm (though I'm no expert here).
>
> Andrew

--
A. Miguel Calvin
mcalvin@ican.net
Guelph, Ontario, Canada
83.5 1.9l Westy