While the change in viscosity of lubrication oils with change
in temperature can be
reduced by the
addition of certain
long chain polymers, such use in
gear oils is not
common. Such polymers when subjected
to the shearing
action of gear sets degrade and form
shorter chain compounds
which are less effective than
the original additives. These agents may also function as
pour depressants. The reason the
polymers in question are
effective is that at low
temperatures they are
coiled up and
only colloidally dispersed. As
the temperature increases
the polymers uncoil and
go into solution
to increase the
viscosity of the mixture.
