I designed hydraulic cylinders for many years, which use a lot of o-rings and elastomer seals in a variety of materials; mostly Buna-n nitrile and viton, which is high temp rubber. My understanding is that the o-rings and seals in a tank can be a variety of materials, including Buna-n, viton, and silicone. In the hydraulic cylinder industry we used grease for assembly purposes of these types of seals. Specifically, we used Vaseline. Makes stuff go together nicely and doesn't hurt these materials, which are designed to use with petroleum products.
DON'T use Vaseline to lube your vape seals. Petroleum greases and oils are toxic and while they will preserve your seals nicely, they will contaminate your vape gear. Use what your juice uses for a diluting agent, which is PG or VG. They will be just fine for years that way.