I have a 2010 v6 with 179k miles original chains oil changed at 5k mile intervals since it had ~75k on the odo. before 75k I just went by when the dash told me. now I do have a ticking noise only when the oil is cold (less then 30f) and it goes away once warm. this tick has been there for ~115k miles and hasent gotten worse. I also do not have the chain rattle during acceleration like the typical 4.0 rattle will have. so as long as you change your oil and filter regularly you should be fine. oil brand and type (full syn or semi syn) doesnt matter as much as long as you do regular oil changes. I would say that a quality oil filter is more important than oil brand.
btw around 2016 I got a quote from a dealership to do the chains it was around $4k back then i cant imagine what it would be now. an independant shop may be cheaper. if you are not doing the chains yourself then it may not be worth it. they require a special set of tools to hold the camshafts in place so you dont loose timing. last i checked the tools where $500 alone. the reason for the expense from a shop is the engine or transmission has to be pulled from the vehicle (preferably the engine) to get to a cover where there is a bolt that holds the rear chain sprocket to the jackshaft. if you do the chains yourself they can be done without removing the engine but the transmission has to be removed and it is very tight working conditions.
In case you want to know what oil I run its full synthetic pensoil platnium price wise this is the cheapest oil I have used and reduces the startup tick. I have also done used oil analysis' on this vehicle with different oils and the oil reports come back very similar to each other and thats good. really the only metal that varied alot was iron and that was do to how much idling the engine got. In case you are wondering the other oils i have run they are royal purple, amsoil, schaeffers oil, valvoline, and redline. redline was the most expensive at a little over $80 just for the oil and the report for it came back with the oil a little thinner than a 5w30 but everything else looked great.
lastly if you want the piece of mind and are going to drive it till the wheels fall off then get the timing chains done. if not worry about other things like the transmission.
