Axman: you obviously know what you're talking about so this is just to add a little something to the discussion and in no way critical of anything you posted.
One of things we discovered there was that in some cases lock washers would actually cause bolts to loosen under certain conditions. The theory was that the lock washer reduced surface contact area and when combined with fretting would reduce it's spring tension allowing the fastener to loosen.
I also tend to use anti-seize on many fasteners, but doing so obviously reduces the friction between the threads and makes it easy to over torque the fastener.
As to Loctite stressing plastic, I've never considered it, but it makes sense that as the Loctite hardens and expands slightly it could create issues. And I agree using petroleum based products around any plastic never seemed like a good idea.
Thanks for saying that, but it's probably more accurate to say that I "think" I know stuff, but find out all the time that I don't. I find that I learn a lot, by making dubious statements (not intentionally) and being corrected.
That item about the lock washers make sense. One thing is for sure, my RE C5 is a reliable tester of fastener security. More than one has gone MIA, the worst offender so far, being the nut preventing the rear brake drum from spinning. It spun, the brake locked up, there was much cursing.
The anti-sieze has become SOP with me. I grew up in Cleveland, OH, and Chicago is almost as bad a rust breeding environment. I hate the suspense of trying to remove rusty bolts on the old beaters I have driven all my life. Will it loosen? Will it shear? Will my socket crack or my 1/2" extension break? The acetylene torch and Kroil gun are my constant companions. I remember hearing somebody say, many many years ago, ... " I never grease wheel studs, the rust helps hold the lug nuts on!". I didn't buy that nonsense, even as a 15 year old. This stuff is my pal:
https://www.amazon.com/Permatex-80078-Anti-Seize-Lubricant-Bottle/dp/B000FW7VGE/ Stress cracking in plastic isn't exactly mechanical stress, and it isn't entirely chemical attack. It's a combination of both factors, and every time I've seen it in action it has totally blind sided me. Remove the stress and the chemical won't attack, remove the chemical and the stress is manageable, but together, big trouble. Here's a write up describing the phenomenon in some detail.
https://www.plasticstoday.com/materials-analyst-part-22stress-cracking-how-avoid-silent-killer-part-1I had time to do more research. I was correct about Red Loctite 271 and Blue Loctite 242. Both carry the mfg's warning "Not for use on plastic parts, particularly thermoplastic materials where stress cracking of
the plastic could result".
https://dm.henkel-dam.com/is/content/henkel/TDS-209741-US-Loctite-Threadlocker-Red-271-Carded-Tube-0.20-fl-oz-2018-04-09pdfhttps://dm.henkel-dam.com/is/content/henkel/TDS-209728-US-Loctite-Threadlocker-Blue-242-Carded-Tube-0.20-fl-oz-2018-04-09pdfI suppose it's probably the Methyl methacrylate causing the problem? I see that the stuff also contain Saccharin, no idea why, and some other ingredients that we need to be warned about.
https://ypsswhdoal-a0d0758e9.dispatcher.hana.ondemand.com/SAP_GATEWAY/odata/SAP/YPSSWH_DOO_SRV/SafetyDataSheetSet(Appid='YPSSW_SDSUA_EXT',Matnr='209741',Laiso='EN',Rvlid='US',Dmskey='')/$value
The fact that regular Loctite is incompatible with plastic is probably why they invented Loctite 425, which is expressly compatible.
https://www.all-spec.com/Product/135461-30769