Yes, that is the problem with normal hydrocarbon based grease. It
isn't well suited for gear or brake wires. This is why I, my LBS and
Shimano recommends _Silicone grease_, which isn't a grease in the same
sense as normal bicycle grease, as the perfect solution for
lubricating gear wires and cable housing; it prevents freezing,
corrosion, water ingress since it repels water and acts like a
waterproof seal, it lubricates, doesn't attack or swell rubber o-rings
or the cable housing, it doesn't separate or coagulate, doesn't stain,
is non toxic, it has low chemical reactivity but high thermal
stability, so it doesn't decompose easily because of age or chemicals
or oxidation, and it doesn't attract dirt the same way as regular oil
or grease does, nor does it stiffen up when cold.
All in all, Silicone "grease" is the perfect lubrication and anti-
corrosion agent for bicycle wires no matter what the weather, which is
why bicycle cable makers like Shimano or Campagnolo supplies it with
their cable sets. It is superior to hydrocarbon based oils or greases;
Chain oil or WD40 may lubricate a gear wire well, but only for a short
while, then the eg. wax in the WD40 or the attracted dirt will clog up
the cable housing and increase friction considerably. The mixture of
oil and dirt also works as an abrasion agent so the wire will start to
cut into the housing.
The Silicone grease plumbers uses for sealing faucets or o-rings etc,
is usually of the right consistency (NLGI 2-3) and can be had quite
cheap. Tubes are better than tubs.
--
Regards