Steve's reply to your post was great. I've never read one of his replies that I didn't enjoy, and more often than not, you learn something valuable from them.
Some months back, this same type issue came up, and Benzmac indicated that he showed the salesperson to the door who was trying to sell him such a contrivance. His conversation went something like; he asked the salesperson what the system would do for his customers, as many salespeople, he didn't answer the question as asked. Instead of answering what the system would do for his customers, the salesperson answered that it would make him alot of money. Benzmac showed him the door.
Frequent oil changes is all that's necessary to keep your engine clean inside, or get it that way for that matter.
Change oil hot and change oil often,
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in