I get this weird rattle during a cold start. It sounds like something is loose. Ive had some lubricant put in with the oil when its been changed and its helped, but only for a short while. Belt, timing chain...? Any ideas? Ill upload a video in the AM when the truck has been sitting over night.

 

Have you been using 5w20 oil and Motorcraft filter?
Timing chain tensioner guides could be worn.
Rods or Main bearings could rattle a bit until oil pressure comes up.
Sounds like the lack of oil pressure until it builds if you say oil additive helps some.
The 5w20 is needed to help oil pressure come on faster, reduce chain guide wear.
The MC filter is needed to help with drain back.
If this sked has not been used, the wear has already taken place.
Good luck.

 

I have this problem as well. It will usually happen if the truck has been parked overnight... winter or summer. I'm running 5W-20 and a Motorcraft filter... Still rattles for less than a second during startup.

After searching this site, the timing chain tensioner seems to be the most likely culprit... something to do with the oil bleeding out when the engine is off?

 

something like that.