Hi Scotty,
I have a 2012 Dodge challenger with 85k miles on it. It has a 3.6 V6. It runs great and I have changed the oil at recommended intervals and sooner. The maintenance schedule recommends to change the metal timing chain at 100k. It is an interference engine. But you have mentioned that metal timing chains don't necessarily have to be replaced on some of these types of engines. If I decide NOT to replace it, what would be the red flags which I should look out for before the chain fails. Also thank you for your past advice & tips. It has helped me in many ways!
I would change it according to the user manual. Realize that your engine is interference and if the chain brakes, it means good bye engine.
Regarding the signs, look for chain rattle.
Warning signs for a new timing chain are -
Over 100,000 miles
A rattling noise at cold start that goes away in a few seconds.
On most engines the timing chain will last the life of the engine if maintained properly (regular oil changes). However there are some poor designs where the chain will wear out no matter what you do. If the manufacturer tells you to replace the chain at 100K miles they're telling you that it's not very well-designed and you'd better do it.
