Why does nobody talk about quenching in old motor oil for leaf springs?

I was stuck with a broken truck spring in Boise and tried quenching it in used 10W-30 from my garage. The temper came out perfect and it held an edge for six months. Has anyone else tried this with other scrap steel?

2 comments

2 Comments

river_scott7d ago

Honestly the carbon content in the oil might be the secret. Old motor oil has all those broken-down additives and soot suspended in it. It's basically a dirty, thin carbon quench. I bet that's why it worked on your spring steel, it's not a clean fast quench like new oil, it's slower and dirier. Might be perfect for stopping cracks in junkyard steel that's a mystery metal.

reese867d ago

That's a fun idea but honestly it sounds like making a virtue out of a flaw. Used oil is inconsistent by its very nature. One batch could be full of soot and fuel, the next might have coolant or water in it. You're basically adding random stuff to your quench and hoping it helps. New oil is made to have a known cooling rate for a reason. If you want a slower quench, just use a proper quenching oil meant for that job, or even try warm canola oil. Relying on junk oil is just asking for a weird, soft spot or a hidden crack because of some contaminant you didn't see.