re: 2011 Ecoboost Timing chain rattle

I've replaced them on SBF and SBC engines with as little as 50k miles on the set. In older engines you simply could get away with the minor changes in cam timing and the old EFI systems didn't have the resolution to see a problem until it was something major. Practically all modern OHC V8's and V6's can expect to have a timing chain replacemt or tensioner/guides replaced if the owner wants to keep the engine long enough. Big thing with these engines is using the right oil and good filters and changing them out regularly. I stick to a 5k mile OCI with full sythetic oil and OEM filter, oil life computers don't seem to be good enough and is a major culprit with GM's V6 in the Colorado.