Rick wrote...

Oil, grease, etc can spontaneously combust in an oxygen rich
environment.

Want to try an experiment - Shoot pure O2 from an oxy/acetylene torch at
an oily/greasy shop rag.  Be prepared for fire.  Thus, caution when
using a torch with dirty (greasy) jeans and don't introduce ANY oil into
your o2 system.

Seems there was once even a warning about not using lipstick and oxygen
together as the lipstick had a somewhat greasy base and could ignite
when bathed in O2.  (Myth???)
------
I understand that oils will oxidize (light, more volatile petroleum
products do so faster than more viscous products, such as grease) and in
a pile of rags, the slow oxidation can eventually generate enough heat
to cause spontaneous combustion, but I'm not sure how that phenomena, or
the torch analogy, apply to our aircraft and cockpit.  Nonetheless, your
points are well taken and in the interest of safety and on the side of
caution, I'm not going to wear lipstick when I use oxygen.  :-)

Chuck