I use a moly grease lube on my hinge pins, although I have used a freebee Krieghoff oil that was fairly thick on several hinge pins. Some worthies on the Practical Machinist South Bend Lathe BBS have switched to Mobil 1 0W-20 for their headstock spindle oil, as I have. This Mobil 1 oil has gained a reputation among that crowd for being extremely slippery and reducing friction and resultant heat.
If I was FORCED TO use oil instead of grease on my hinge pins I would find a Mobil 1 oil approaching the 80W-90 gear oil I use in my 1950s Johnnyrude outboard motor gear cases.
Just my $0.02 - your mileage might vary.
I have always used oil but after reading Ian's post I think he's right and I'm going to use grease because the weight of the barrels is swinging on the hinge pin. I recently saw a rather nice Elsie hammer gun and was thinking of purchasing it until I opened it up and saw the hinge pin/barrel under lug were clobbered out. Ian you might want to look at Chevron grease. They make a knockoff of the old Amoco Rykotac grease. It's a long fibre grease that I use in driveshaft knuckles. Like Brylcream, "A little dab will do ya."
I belong to Practical Machinist too Ian, and I use straight 20 weight non-detergent in the headstock of my Monarch.
