I use my FSS, but not quite as MB intended.
Every 5000 kilometers of countdown, I change the oil. That way, if the computer counts down faster due to stressful conditions, then I change the oil more often.
Then, when the FSS counts down to zero, I do either the A or B service and reset the FSS to 15,000 kilometers.
At the A service, I change the cabin air filter AND the engine air filter.
Also, with your 722.6 five speed tranny, you would probably want to change the tranny fluid and filter every 90,000 kilometers or so. It's NOT really fill-for-life. Dan covered just about everything else...
1998 C230 "Black Betty"