Pour Point Depressants

Certain  polymers when  added to wax containing lubricating oils in  proportions of 0.1 to 5 per  cent, will  alter  the  crystal  structure  of the  wax  and  thus  permit  movement  of the  oil  at a much  lower  temperature  than  before  the addition. Some  agents  used  for  other  purposes, for  example V.I. improvers, may  have a similar  influence on  pour  points.

Most  industrial  gear  oils do not  require  this  type  of  additive but  pour  depressants are  often  included in  automotive  gear  lubricants. The agents  normally  used  include  “Acryloids”  which  are  methacrylate  polymers,  and  “Paraflow”  or “ Santopour”  which  are  wax condensation  products with either  naphthalene or  phenol. 

Overrunning clutch lubricants

 The  freewheeling  clutch is  probably  a  thing  of  the  past  in  automotive  vehicles but  still  finds  some  use  in industry. Therefore, mention will be made of the characteristics of oils   required for this service. Such  a  clutch  will  be  a  part  of the  driving  mechanism  and  consequently  will  logically  be  lubricated  with  the  gear  oil  in the  case.

However, there  is a limit  on  the  viscosity  and pour  point of a  satisfactory  overrunning  clutch  lubricant  as  recognized  by  Roos  and James  who  stated:

“ If  excessive thick  lubricant is used  the  roller clutch will not operate  in cold   weather  until the car  has been  driven for  one  or two  blocks  with the  transmission in  positive  engagement.