For my razors in rotation, I used to do nothing. While for those in storage I used mineral oil.
Notice that the above is past tense...
Currently I have all my razors treated with Ren Wax. One weekend I cleaned off all the oil and everything I owned got a coat. Incoming razors get a coat after honing. Pasted balsa and linen and leather stropping probably remove a patch at the spine and edge, but I haven't seen any issues. I do notice less tendency for water spots to form on the width of the blade.
Notice that the above is past tense...
Currently I have all my razors treated with Ren Wax. One weekend I cleaned off all the oil and everything I owned got a coat. Incoming razors get a coat after honing. Pasted balsa and linen and leather stropping probably remove a patch at the spine and edge, but I haven't seen any issues. I do notice less tendency for water spots to form on the width of the blade.