Have you checked what weight oil you're running now versus what you had before? In my experience, that startup noise after switching back is usually because conventional oil is thinner when it's cold, or the old engine might be used to the better film strength of synthetic. I've seen plenty of high mileage trucks that run quieter on synthetic because it doesn't break down as fast and leaves less sludge. Your buddy means well but every engine is different, especially after 100k miles. I'd say go back to synthetic for one change and see if the noise stops, your engine will tell you what it likes.

Two months isn't long enough to make a call on this. Give it a year or two and see how that PVA holds up against humidity changes and natural leather movement. That's the real test, not adhesion straight out of the gate. Plus, PVA is basically plastic glue, it doesn't breathe like paste does and it can turn brittle over time on flexible materials. Your bad batch of paste was bad luck, not proof that paste is worse. Stick with what the old timers used for centuries before the chemists got involved.

...actually that's not entirely right about the Park Tool SW-0, it's really meant for 0 gauge spokes which are pretty rare on an old Schwinn. Most older Schwinns use 14 gauge spokes which need a 3.2mm or 3.3mm wrench, not the SW-0. You probably should have grabbed the SW-2 or SW-7 instead. I've made that same mistake before and it just makes things worse because the wrench doesn't fit right and chews up the nipples even more. The cheap ones definitely suck though, no argument there, but even a good tool won't help if it's the wrong size for your spokes.

Disagree with you there @wren_brown. I spent good money on that lens, I want it to perform right across the frame. Dust and smudges are one thing, but a design flaw that kills sharpness in the corners is different if you shoot landscapes or anything with a flat field.

Are you sure that plastic clip was really that hard to get at, or maybe it was more of a "tools weren't in reach" kind of morning? I mean, I've definitely had days where a simple screw turns into a saga, but three hours for a clip sounds like a lot of extra time spent. Sometimes you just need to walk away for a coffee and come back with fresh eyes, you know? Was it a pain to reach or did you just get unlucky with a stuck bolt on the clip itself?