I started with a piece of automotive leaf spring. Shaped and sanded to my desire. Now I want to harden and the anneal the steal. All I have at my disposal for heat is an oxy-acetylene torch. What oil do you use for quenching? How do you know when the steel is the right temp for hardness? How about signs of proper annealing?

The leaf spring is probably 5160 steel. First I would Normalize it -heat uniformly with the torch to just above nonmagnetic and cool in air.The non magnetic point is 1414F, just touch a magnet to the steel.To harden heat again to just above nonmagnetic and quench in a motor oil ,a 20weight oil works fine.Temper in your kitchen oven 2 hours at 400F.