Nah I'm gonna play devil's advocate here and say the supervisor had a point even if he was a kid about it. 42 is past prime for commercial diving, the statistics back that up. Your 3000 dives are great but the body doesn't bounce back the same way at that age. He probably saw a safety report or two about older divers getting bent or having heart issues under pressure. Plus you coming back with the log book dick measuring contest just proves you're the type who won't listen to anyone younger no matter what. Maybe he was an ass about how he said it but the core message was valid. I've seen guys in their 40s and 50s get hurt doing jobs they could handle at 25, it happens more than people admit.

Good for you for finding that trick. I've been a barber for over a decade and I learned that one the hard way after ruining a really nice set of Wahl blades. Mineral oil is the way to go, it doesn't get gummy like some of the specialty sprays and it keeps everything moving smooth. A drop on a paper towel after each shampoo cut has been my routine for years now. It really makes a difference in how long the blades last.