If you listen to only one of my rants, make it this one! Aluminum antenna elements typically telescope into each other. The assembly instructions often make some sort of vague comments about lubricating the joints with petroleum jelly or grease. FUGETTABOUTIT! There is only one product to use for this purpose, and failure to do so will cause a lot of difficulties at a later time. Penetrox A is a specially formulated grease that contains tiny zinc particles that ensure continuity between the elements and prevents corrosion. Joints that are not properly lubed will quickly corrode and likely freeze together. If you are lucky this will just leave you with an antenna that can no longer be disassembled and re-tuned. If you are unlucky you will have created a capacitor with a wonderful crud dielectric that means your antenna is destroyed.
Penetrox A can be a bit hard to find. Check with electrical supply houses, and if all else fails, order it on-line. A small jar of it will last the rest of your life - you don't need much. To use it, take just a dab and make sure that all mating surfaces have a light coating. I have taken apart antennas that have been treated with Penetrox A and have been in exposed locations in our Puget Sound corrosive atmosphere for over 30 years. They came apart every time!
This is a product that can be used for other applications.
If you install a tower such as Rohn 25 you should lube the mating sections to ensure continuity and to facilitate disassembly in the future.
You often have to bond body parts together in mobile installations to ensure that you have a good ground plane. This is typically done by connecting the parts with short pieces of ground braid with solder eyes on the end. Use stainless steel screws and star washers on each end and a tiny tab of Penetrox.