I realize this post may be beating a dead horse but search didn't quite turn up the answer for my question. Once the warmer weather arrives here in the north I'm going to be changing out all the fluids. Now while I use Mopar fluids for the transmission, transfer case, radiator and power steering, I like to use Amsoil for everything else as a friend of mine is a dealer. I haven't yet done work on my WK since it has been frigid out, but my question is, for the QDII diffs is it best to use the Amsoil 75W-140 gear oil with the 4 ounces of Amsoil limited slip additive, or use the Mopar limited slip additive for the ELSDs? I tend to play it safe and use Mopar but I'll be getting a really good deal on the Amsoil products that I've always loved, even more so than Royal Purple. Just want to hear what people think due to their own experience.
Related question... Has anyone used Pennzoil Synthetic 75W 140 without adding extra friction modifier? If so did you have any chatter or binding? I just bought a 2005 WK Hemi w/ QDII and am preparing to get the fluids changed, etc... Not too many service records provided but one is from a quick lube place that shows a rear diff service and the Pennzoil Synthetic 75W 140 as the fluid used. No friction modifier added. I called them and they claim their computer doesn't show that the FM is needed for that model. Their report also showed that the front diff and the transfer case were N/A, so they obviously have some bugs to work out. I can see from the Pennzoil website that the Synthetic 75W 140 is good for LSD, but was wondering if anyone had first hand experience using it without FM. Would like to know if I should be concerned about worn out clutch packs. WK has 114,000 km's. Service was 14,000 km's ago.