So you have the 8 speed and not the preheated diffs, I believe that lovely piece of science is in 5 gens. So redline D6 is compaitable with zf8 fluid in performance, but is cheaper. The zf8 fluid is actually a good fluid as well, you will just pay a lot more for it. If it were me, unless there was an issue, I'd probably wait til I had near 90k miles on zf fluid before changing.
Diff fluid in most cases is 75w140
(
this one) in rear and 75w90 (
this one) or close in front diff for the 1500's. Make sure you don't get the NS redline, those are the ones you want, see oem specs page. So either redline or Amsoil SG or even m1 will be good choices of Mopar diff fluids, much paper out there suggests mopar gear fluids are a pass. Diffs are funny, because you can get contamination in them, guys should be poping the rubber gromet every 6 months and checking the fluid warm to make sure the fluid sits down, no foam or water intrusion.
Brakes, all fluid is hydroscopic, cheap brakes fluids boil at 330f, which is fine you wont boil your brake fluid. The issue is overtime, unless you do brake flushes every 3 years like most manu's recomend, your fluid degrades, even redline will degrade over time. The thing is Redline starts at a higher boil temp, so even if it falls off it wont be getting to 330f unless there is something wrong with the system and you are getting too much water in there. However, the cheaper brake fluids degrade and braking is comramised ovetime. Two weekends ago my good friend came over because he was "losing his brakes". He wanted to do pads, but his fluid was black so I insisted we do fluid as well. We did the pads and drove around, still was janky, we flushed the fluid just with the cheap stuff he is a cheap *******, 16 ounces then 32 ounces, two flushes, his brakes were like brand new. Now, he put's off maintenance, if he would have used redline his brakes likely wouldn't become janky in the first place, it will take a lot longer to get brake fade with good brake fluid. Doesn't have to be redline, in syn thread there is a list of brake fluids and starting boiling temps for dot 4, any of those will serve you well when the starting boiling temp is 400f plus.
Redline s1-1 uses the same stuff in techron, just more of it. Goes in fuel and also has carrier oil so it helps with cleaning. I would use it a few tanks before your oil change. Techron and Amsoil PI will likely do some cleaning as well. Think detergent versus solvent, PEA the active ingrediant is a detergent, it is more effective then a solvent. Gas itself is a solvent, adding 16 ounces solvent to a solvent will only be so effective. Just find a PEA fluel cleaner once a month or so, should keep those plugs clean.
