Same here. The guys at the saddle shop know me very well by now! :-)

The danger of oil quenching is that it may "flash" into flame at the surface. Motor oil will definitely do this on occasion. I've no idea how likely this would be for vegetable oil, but I'd be very careful. Quenching oil has a very high flash point so the danger of bursting into flames is very low.

You can't harden without an acetylene torch...propane won't get it hot enough. Any shop that has an acetylene torch will probably have a bucket of quenching oil. If not, water will work, and since these blades are really thick the danger of cracking or warping is low.

BE CAREFUL! This is a dangerous operation and best left to someone who knows what they're doing. Check the link below for a good discussion of the process.

http://w3.uwyo.edu/~metal/heat.html

Bill