@rgranger Would you be able to shed some light on the chemical compatibility of PTFE based lubricant on a nitrile o-ring? I'm not seeing any compatibility charts that list those two together.
I'm also curious why PYI/PSS says not to use oil based products when nitrile is generally compatible.
The prop shop I went to said that lubricant on the shaft/coupler causes a suction effect. I guess it's because of the small grooves left over from machining? I feel like the likely hood of this happening is pretty low with a coupler that's open on both ends. I've seen this happen on greased automotive parts where the end of a shaft goes into a socket. This generally happens when a part is over greased and it wont go all the way in because it's being hydrolocked for lack of a better word.
If lubricating splined axles and shafts is the norm to prevent seizing, then I doubt it would cause any harm to a keyed shaft. I suppose it would make the key slip into a different position more easily but if it's enough to cause an issue, there was too much play between parts to begin with. I'm speculating so if there's anyone with more knowledge on the subject, I welcome your expertise