The shop manual is very clear on this subject: If the car is equipped with air bags DO NOT lubricate the slip rings.
Apparently this could cause the air bag to not deploy when needed or possibly cause an errant deployment (although MB is not known for errant deployment).
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.