Rear differential and transfer case are a no brainer for me, mainly because I’ve always stuck with 30k intervals on my other vehicles under relatively “severe service” with good results. And though my wife’s cx-5 doesn’t quite see the same duty as my work trucks or weekend toys, the differential has a much smaller capacity (<1 qt vs 2 qts or more in the other vehicles) in the cx-5. Combine that with several reports of them potentially being under-filled from the factory and I think it’s worth checking/changing the oil at 30k.
As for the transmission, agree completely on the lifetime fluid claim. My folks were the victim of this claim with their first Mercedes, which ended up needing a new tranny at 120k on the original “lifetime” fluid. Also saw plenty of bmw’s and MB’s of that era with burnt up transmissions while working for the respective dealerships.
I’ve noticed more so in the last 5-6k miles that the transmission on our cx5 downshifts a bit abruptly into 2nd gear when braking to a stop. It’s like I can feel a slight “thud” at about 5mph under braking. Not sure if this is just a characteristic of the 6spd auto, or could be indicative of a transmission issue.
Would normally wait until 60k to service trans, but was thinking of moving first service up to 30k because of the possible issue above. But now I think the best course of action would be to service transmission at around 50k and have old oil inspected or maybe sent in for analysis. That way if there’s any indication of a problem, there’s still some miles left on the powertrain warranty.