Started a thread a while back about a knocking sound in my 95 6.5T. Turned out to be a cracked valve. Took both heads to the machine shop and had them reconditioned. Now I just have to put the turbo and upper intake on and change the oil. What is the best brand oil to use. I know to use 15/40 some say that rotella is the best just wanted some opinions.

rotella T 15w-40 or dello are good but 5w-40 synthetic has better overall lubercation.

rotella T 15w-40 or dello are good but 5w-40 synthetic has better overall lubercation.
Modern dino oils nearly replicate all advantages of syn except extended oil interval, millions of HD OTR truck miles using Rotella or DELO is proof positive that advantage of syn over dino not worth the expense IMO, regular oil change at reasonable interval is sufficient. Boils down to a matter of choice only you can decide which is best for you.

when i had my 6.5td, i used mobil1 15w50 in it... seemed to work best for me from the various oils i tried [i did somewhat extended oil change times 2x per year]

a 50 weight is thicker than recommended for the 6.5. my best suggestion is to use what is the most widely available in your area and change it more often. dino rotella and delo 400 and mobil delvac are all real good bang for the buck 15w40 oils.