This is not advice but a tale of a solution found through necessity. When Ice riding in the winter back in the 80's, our Rear derailleurs would often freeze up and refuse to move when asked to. We found urine freshly applied from the source to be an effective de-icer. Note- Urine is not a lubricant. But it will unfreeze your derailleur. Works at below 0'F temps BTW. I should mention that immdeiately following a frigid ride where urine has been introduced to the drive train, a quick rinse post ride with fresh water always seemed a good idea.

As to chain lube. I agree with the SRAM tech mentioned somewhere earlier. I find thinner to be generally better. And good lube need not be expensive or bought from a bike shop necessarily. Although I do appreciate the customers who rely on me to supply their lubrication needs.