I'm going to oil bathe this shimano nexus 7.. the proffesional bike repair person I asked to do this for me sprayed wd40 in it, €80 later I decided to just buy
SHIMANO NEXUS Internal Geared Hub SG-C3000-7C SG-C3001-7C and Shift Lever SL-7S30 SL-C3000-7 7-speed Original parts - AliExpress