Treatments like a Motorvac or Terraclean basically aim to clean out the combustion chambers, intakes, etc through running a cleaning solution as gas and letting the engine run.
I think a few of us have done the treatments, and have been pleased. But, some people said it made no difference in the long run...except $100 to $200 poorer.
If you've been good in keeping the maintenance, then maybe it's one of those "I'll do it whenever" deals.
But yeah...I'd keep an eye on the clutch.
