I can't find the original source but Scott @ TRF says the calibers in 50 year old rolexes have a 5-year service interval: https://www.rolexforums.com/showthread

I can't find the original source but Scott @ TRF says the calibers in 50 year old rolexes have a 5-year service interval: https://www.rolexforums.com/showthread.php?t=679777 https://www.rolexforums.com/showthread.php?t=679777