There is a small oil leak at the oil cooler seals which will be sorted at the same time. At no time has the car shown up that it needs more oil. Surely not enough to affect the tensioner.
Car shows no fault codes/issues (incl low oil pressure/level) but sometimes doesnt start first turn of key. When it does you can hear noise from front of engine. No sound after that.
Local MB Indy is well known to me, trusted and has good reviews....