On Wed, 16 Feb 2005 21:24:53 -0000, "Newshound"
wrote:

Well, grease is an oil which has been "solidified" by mixing it with a
thickener, so that it doesn't run away through clearance gaps.

Mineral oils are cheap and are good lubricants for metals. However they are
also a bit biologically active so you try to keep them away from food and
skin. Lithium greases are made from mineral oils and have a relatively high
melting point, so are good for things like car wheel bearings which get warm
because of the high speeds, and the proximity of brakes.

Silicone oils are more expensive and are poor lubricants for metals, but
good lubricants for plastics. They will also ultimately withstand higher
temperatures than mineral oils (and don't catch fire). You make silicone
greases from a mixture of shorter and longer chain silicone molecules.They
are biologically inert so are good for lubricating plastic fittings (such as
drinking water joints, taps).

Axle grease is too loose a term. In olden days (carts with wooden axles)
they would have been made from animal fats.

Very informative - thank you! I undestand that mineral oils (and
gease) rots rubber. What about silicone grease? Is that safe to use on
rubber? And then there is neoprene (as often used nowadays in place of
rubber for seals and o-rings. Which greases are safe to use on that? I
think you might know the answer.

Thanks again,

RickyC