Might help to know where you are as well. Especially since in the US there has been NO leaded fuel for at least a decade, and the UK is soon to be dropping it as well (I believe). Going from leaded to unleaded is no problem since MB has used hardened valve seats for a very long time.
'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.