That's very true Stormy. The dry lube coating would be the ideal in this situation. It is also used extensively in the aerospace industry where components are not easily reached for lubrication but absolutely must not sieze. If had to spec it out on numerous parts such as missle release hooks for the F4 Phantom (years ago). Imagine the pilot arming a Sidewinder and firing only to have the missile release hook lock up! Bummer!
The nitriding of the shaft would add tensile strength and wear resistance to the surface of the shaft to a depth of about .025" much like the hard anodize process for aluminum.
The biggest drawback to these processes is the cost. Most companies that do this type of hardening and/or coating usually charge a 'lot' charge averaging around $80 just for setup on each run. Then it's charged by the pound of material. To be cost effective you need to have volume to amortize the cost over say a hundred parts so the that the individual item cost remains reasonable. This holds for almost any process in manufacturing.
Bent, the jet turbine oil is a good candidate as it is a 5W oil that will flow into the crevases between the fingers and axel. The caveat is that it is still a 'wet' lubricant and as such will have a tendency to collect dust. Given the design considerations of any PSG changer, this is going to be an unavoidable issue. Someone needs to design a 'sealed' changer! Another good choice for this application is '3in1' oil. It's readily available and fits the application criteria. It cleans, lubricates, and protects against corrosion. If you can find the '3in1' electric motor oil in the blue can, it seems that this would be the best as it has the same characteristics but a slightly higher viscosity at 20W.
Just as reference, there is almost no aluminum in a turbine engine as the operating tempuratures are far too high. The cold side compressor section is primarily titanium and the hot side is mostly high temp nickle alloys and stainless with the gear cases being magnesium.
Back to the theme of applications, I found an article about live steam model locomotives where the author discussed the use of different lubricants in their realm. I found it interesting as most of what he said can be applied to many applications. here's the link for those interested
http://www.southernsteamtrains.com/notes/lubeoil.htm.
3in1 oil is made by the same comany that makes WD40 but 3in1 dates back to 1896. WD40 is a no-no for the PSG. It is a cleaner, penetrant, and water displacement product not intended for lubrication. It then it gums up in time as all the volatile components evaporate.
To sum, yes the jet oil should be good.
We would always want two components that are in contact with each other to be of dissimilar types. One needs to be softer than the other to allow wear to a certain extent. I believe that Richard stated that he would prefer a stainless shaft and fingers. That's really not a good idea due to the fact that stainless is designed for corrosion resistance and has a tendency to be 'gummy'. This may not enter into the equation on a changer due to the lower operation forces but my experience has taught me to never apply two stainless surfaces in a friction situation as you will very quickly have metal transferrence, i.e. galling. The same would hold true with aluminum, brass, titanium, all to varying degrees unless one component had been surface treated to be harder than the other.
Think about all the mechanical mechanisms you've ever seen. How many times have you ever seen similar materials in direct contact with each other in a load bearing/friction situation? Let me qualify that with 'quality' mechanisms.