My Jeep definitely seems to run quieter with xw40 weight oils. PYB 10w40 is one that I've had great luck with in terms of noise reduction and there's a few UOA's here showing pretty dang good results. Currently running 10w40 Castrol Syntec and have some Castrol Edge HM 10w40 for next time. Both are A3/ B4 oils. Somewhat comparable to T6, TDT etc. I'd say.
I run M1 TDT 5w40 in my dad's Renix 4.0, but it has just under 90,000 miles too.
In terms of startup noise, the #1 culprit seems to be the filter choice. Sadly, my Jeep hates WIX filters. I've tried the Napa Silver and Napa Gold. I used to have really good luck with the Mopar filters, but they turned out to be as noisy as a WIX. I always go back to some sort of Fram filter. With this run of 10w40 and the Ultra, I've experienced a few start up rattles, but the temps were just below 0*F. Doesn't get much colder than that here.
*I might give 15w40 a try in the summer. Run it from say April to September.