Originally Posted by
ArchaicArcane
I've often thought about this. Here's what I understood from various sources:
But old dry nylon / plastic is brittle. Wouldn't grease help prevent that? I've had broken nylon gears to replace and as many or more were dry than were greased. The ones the lady tried to sew through saddle leather with her touch and throw don't count in my mind. She exploded 4 of the gears in that one, including the 2 vertical ones.
Also, a lot of the newer greases (like the TriFlow grease) are synthetic. Wouldn't that be less likely to break down the plastic and nylon but still keep it from getting brittle?
I also found it interesting that the replacing gears video from SewingPartsOnline shows the techie guy slather a layer of (synthetic?) bearing grease on the nylon gears he just changed.
I'm on the fence and undecided, so I haven't tried anything, since I'd not likely see the results in my lifetime anyway...
I do think the petroleum break down is or was a concern, but more so the fact that the nylon gears are weaker than metal and the grease can attract "stuff" into them that can cause cracking and breaking. If it's my machine, I know it would be serviced properly and timely so that wouldn't matter. But, handing off a machine to a stranger or someone that will possibly not service it for years, or never....I can imagine how lint and junk could stick in the gears with the grease acting as an attractant.
Me..I don't have a strong opinion either way. I don't grease nylon gears, but I'm not strongly opinionated on the subject. But many techs are pretty adamant it shouldn't be done.