I used XL-17 with my first couple of oil changes and it worked pretty well. I started using Driven FR50 a couple of years ago and it's been completely quiet.
I always thought the XL-17 was internet misinformation.
I had the Gen 1 Coyote - a 2011 Mustang GT bought April 2010 just a few minutes from the plant (I lived outside Detroit). I had the "bbq ignitor tick," a term I coined on the ALLFORDMUSTANGS forum. First internet misinformation: I suspect that many of the "Coyote ticks" you read about are different than the tick I had.
Since I was close, they sent an engineer to look at my car (Summer 2010). They put a black goo in the crankcase, and the tick immediately went away. But, the dealer rep told me the bottle was unmarked and that the engineer would not tell him what it was. Second internet misinformation: When I reported my experience on the forum, many speculated it was XL-17, but there was no proof. When others bought the XL-17 on their own for their own self-described "Coyote tick," there were mixed results.
For the record, the engineer had said the goo would help break-in and the tick would be gone by the time the car had 10k miles. It did not. Instead, it returned when the oil was changed. After a ton of trips to the dealer and an 18 month legal battle with Ford, I finally got a new engine and a cash settlement for my trouble in late 2012.
Edit: Here are a couple of my threads during the saga: