On my rega planar 3 I replaced the stock (80w hypoid gear oil) with 140w Mobil synthetic gear oil (SHC 634) and the sound improved very noticeably.
I think Lucas has the best answer, but it is worth experimenting with viscosity, as a more viscous oil can better damp the bearing, and reduce rocking.
I think Lucas has the best answer, but it is worth experimenting with viscosity, as a more viscous oil can better damp the bearing, and reduce rocking.