In the mid 90's I was employed by the local Caterpillar Heavy Equipment Dealership as a product support rep. One of my responsibilities was pulling oil samples from their rental fleet (SOS). The dealership felt there was enough value in this to pay to have it done. I also got alerts from the oil lab when a customers sampling showed a wear trend that indicated the a failure was about to happen. "Before Failure Repair" was the idea and scheduled sampling allowed high hour use machinery to continue to operate until an indication of a failure required attention. This could allow a customer to schedule the repair, arrange a rental, etc. That minimized downtime. Final drives, bevel gear cases, hydraulic systems, engines and transmissions were all candidates. I remember a hydraulic component failure (boom cylinder I think)on an excavator that ended up costing in excess of $15,000 years ago because of the metal contamination after the failure. The customer did not use SOS, and it may have saved him. As has been said often, you need several to start setting a trend on wear patterns. I bet good sampling history would be a great selling feature when you got ready to sell your boat.