Today's lens coatings are a lot tougher than they were a few decades ago--and in fact some of your old Weavers may not even be coated.
Plain water and clean cotton cloth work well, but a microfiber cloth is better yet, and paper made specifically for lens cleaning also works. Just make sure you wet the lenses before using the cloth.
Various "official" lens-cleaning liquids don't hurt, but aren't really necessary--and on older scopes may harm the lens mounts. The biggie is not to try to wipe off dry dust, or use paper towels, facial tissue, etc. instead of clean cloth, because they contain particles that can scratch lenses.
