Since we are talking about Mobil 1, I will tell you of my conversation I had with them last week. I was inquiring about some products for my recently purchased Jeep Wrangler that now has 3,300 miles on it.
Question: Which Mobil 1 product do you recommend.
Answer: Regular Mobil 1 unless I plan on extending oil changes to 15K, and no need for high mileage oil if I start out on Mobil 1.
Question: Can I use Mobil 1 ATF in the automatic transmission & transfer case.
Answer: After being put on hold (I assume to either look in his book or ask someone) the answer was yes I could.
Question: Can I use Mobil 1 LS75W90 in the front & rear differentials.
Answer: Yes I can, but I would need to add the requires LS additive from Mopar.
Question: I thought your 75W90 had this additive.
Answer: It does, but not enough to meet Dana specs. Add the Mopar stuff.
Question: Can I go longer than the recommended 12K without changing out the gear oils if I use Mobil 1 LS75W90.
Answer: No. Do what Mopar recommends.
I left the conversation at that and thanked him for his time.