Shaving oil. Not new. When I was still wet-shaving and travelling with just hand baggage for work it was handy as you could get it in tiny bottles which didn’t raise any eyebrows (pun in there somewhere ?) at airport security.
Honestly I just use normal soap or even cooking oil. Whatever is in the house. I never buy something marketed for shaving. Maybe it’s just me, I don’t know.
One guy on the shaving forum I look at posted up his recent blade haul. I worked out if he used a blade a week he had just bought enough to last him 18 years… And he already has a good couple of thousand already.