which oil to use in mk 4 forks

[duggy the douglas]

Could anyone advise which oil to use in the forks of my mk 4 douglas,need them to be a harder than they are.
Many thanks

[eddie]

According to the maintenance Manual, the recommended oil for the front forks is SAE 20 (but heavier oil can be used to increase damping).
  If you are finding the springing to be too soft, increasing the damping will probably cause the forks to sit even lower as the Douglas Radiadraulic forks only have rebound damping. Originally, there were also 2 options on fork springs - the standard springs which were tapered on the OD, and a heavier duty parallel spring. Douglas also fitted seats to the top of the springs - now these can be stacked to increase the ride height but wont necessarily stiffen the springing.
  Hope this helps,
                         Regards,
                                        Eddie.

[duggy the douglas]

Thanks very much Eddie,will let you know how I get on.