Warning: stop quenching 1084 in old motor oil, it wrecked 3 of my blades
I used to grab whatever oil was in the shop, including some 10 year old motor oil from my dad's garage in Toledo. After 3 blades came out with soft spots and a nasty scale, a guy at the hammer-in told me the detergent additives in motor oil mess with the quench speed. Anyone else run into this, and what oil do you actually keep on hand for simple carbon steel?