I have 3 early model DCX vehicles and have recently switched from Mobil 1 products to Redline products. After my Son (he works mostly on European vehicles) changed the engine oil in my 06 300CSRT8 and put the Redline in, I noticed the engine was a noticeable amount quieter than it was with Mobil 1. This prompted me to change all of them over. I recently did the transmission services on my two Hemi LX vehicles (one with 90K and the other with 170K on them) and used Redline C+4 fluid and Wix filters. Now days there are a lot of good oils/fluids out there, so there is a lot to choose from. Most of the really good stuff is over $10 a quart though, but most also allow for longer change intervals. With Mobil 1, I changed engine oil every 6K and will keep an eye on it and maybe up the interval to 8K miles. I've always serviced the transmissions every 30K and will probably keep that interval the same. IMO, fluids/filter(s) cost a whole lot less than transmissions and I've never had any issues with any of them.....and they're all somewhat modified and I give them all liberal "exercise" almost every time I drive them.
AmsOil 5W-20 in the engine with my '14 300C, 5.7 hemi and 5 speed NAG1 722.6 auto trans, use AmsOil 75W-140 Severe Service gear lube in differential cavity, and using Mopar issue +4 trans fluid, all good here!