ok, so for the record, limmy's last buy was 101 oil with 203 grease. nubbinator and wfd both like 205 grease, and i'm starting to lean toward a slightly heavier grease. if you look at the application notes and composition documentation on dupont's site, the point of the PFPE greases is to stay stable whilst other things, the PTFE powder and a suspended oil do the actual lubrication. so, the oil actually does things like reduce coefficient of friction and the ptfe prevents wear and keeps separation between the parts.
target temperatures and viscosities are in this document:
http://www2.dupont.com/Lubricants/en_US/assets/downloads/DuPont_Krytox_Typical_Properties_H-58510-7.pdfthe chemical structure of krytox products is in this document:
http://www2.dupont.com/Lubricants/en_US/assets/downloads/Krytox_Overview_LowRes_H-58505-5.pdfhence, i'm thinking 205 for the grease, and then anything between 101 and 103 for the oil. between 101 and 103 there are actually really only very subtle differences in viscosity; the differences are a tad larger 30-ish C, where switch crosspoints are going to sit, but the biggest difference between then is where they really thin out. it they were under quite a bit more pressure, say in high speed applications, it would be quite important to differentiate between the grades, but i can't see a huge reason to prefer one of those three oil grades over another for our applications.