Ive had 2 dieselie jeeps , most of the time they where noisie in cold weather and would get quiet once warmed up.
I used 5w30 moble 1 in them and it seened to help .
they both ran for 50/ 60 thousand miles with the noise so i stoped swetting it .
My 04 rubicon is still quit with 80gs on it . but that is where the noise seems to start .