So, no need to oil the thread or wall of the eye cups?

For cleaning, can I also use sterile 0.9% saline water on lenses?

Better to rinse the lenses with a little water, eg bottled water or under the flow of a clear stream, to remove particles, then just lay a piece of paper tissue on the lens to lift off any excess water and remaining residue; wiping with a finger and cloth as shown at 1:50 is a sure fire guaranteed way to scratch the coatings. I’d never recommend anyone wipe their lenses in that manner, as any remaining fine particles stuck on with whatever will not likely be blown off but are much more likely to be removed under running water, as shown later. Then - LOOK CAREFULLY - BEFORE you start “polishing” (also a mistake) to make sure there isn’t anything remaining in the surface of the lens that might scratch them. Assuming you’ve done this and found them to be essentially clear of particles, then you can pat dry with just the weight of a tissue on the lens, thereafter you can clean the lenses with an alcohol lens wipe, but it’s preferable to wipe across the lens in one direction the use the other, clean side of the wipe for the other lens, before discarding the wipe. Never reuse the wipe, and never rub in circular motion, that only serves to leave either residue on the lenses or can lead to the coatings being scratched from unnecessarily repeated circular abrasion. Clean the lenses in the way that least involves touching them. I’ll do mine, you do yours.

I’ll take mine under the shower and give it a good shampooing.