Most mfrs. have a specific oil that they supply/recommend for their bearings. The requirements vary for the bearings used. A "sloppy" bearing will need a higher viscosity oil to take up the "slop", and close tolerance bearings will need a thinner oil to flow in the very small surface gap. There is no right answer unless you know the turntable/bearing in question.
The best oil to use to lube a turntables spindle .
I just sold a turntable on Audiogon to a person who apparently used atf to lubricate the spindle bearing and the motor spindle. He claims that the motor is making noise now. {It was quiet when I shipped it to him}. I don't think atf should be used to lubricate turntable bearings. I believe it probably seeped into the motor and is causing the noise. I would think light machine oil would be best. The table in question is a Connoisseur bd102 belt drive. Any input would be helpful. Thanks.