T6 is the 5w40, but its on the 'thinner' end of the 40 spectrum, closer to the 30 weight spec. I use just the T6 with a Motorcraft filter. Keep in mind that Rotella (a Shell company) has recently changed their "recipe" for the new specification that has been established. It supercedes the previous general engine oil spec. Keep in mind the new spec is reverse compatible, but the previous oil spec does not meet the newer spec. (I will edit this with references to both specs)
I do not use any sort of additional additives. Almost all of them are absolute garbage and offer no actual improvements. The only time those additives actually provide any assistance is to super cheap "dino" oils that have a poor additive blend to begin with. Almost every single one of the additional additives have proven to do little to nothing to additionally reduce wear (keep in mind the wear tests they proclaim are done on ball bearings and a 1 arm bandit not in actual engines). Used oil analysis when done with these additives have proven almost no positive results, some actually made engine oil worse. People who gained the most from additives have utilized specific additves to address specific problems.
I'm not berating you for using them, you are a free man to do what you wish. My background and my "research" has only solidified my OPINION of additives. Everyone is entitled to their own opinion, even if it is wrong. Mine very well may be.
