We sell two different types of oil for this purpose which are still made to the original SU factory specifications.
The first is SU Damper Oil, which is a straight 20 grade and comes in a handy 125ml bottle. This oil is for use where the carburetter is fitted with a damper inside the piston and can be used on all SU, Zenith and CD carburetters.
SU Damper Oil (125ml), Part No: BDR125S
The second type is SU Dashpot Oil, which is for use in earlier, pre-war, SU carburetters where no damper is used. In the case of carburetters fitted with dampers the oil should be filled to a level just below the top of the hollow piston rod, so that when the damper is fitted it does not displace the oil any higher than the top of the piston.
SU Dashpot Oil (125ml), Part No: BDP125S