Overheard a guy at a hammer-in say he quenches in used motor oil, got me thinking

I was at a hammer-in down in Murfreesboro last Saturday and this older fella was bragging about how he only ever quenches in used motor oil from his truck. Said it's free and he's been doing it for 30 years without a single cracked blade. I've always been a vegetable oil guy myself, mostly canola, and I can't help but wonder if he's just getting lucky or if there's something to it. The smell alone would drive me out of my shop, plus I'd worry about nasty fumes with a hot blade. But he swore the slower quench curve is more forgiving on thin edges, which honestly makes some sense for a beater knife. Has anyone else tried this or stuck with the free stuff out of stubbornness? I'm curious if the trade-off is worth it or if I should just keep paying for the canola.

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wyatt5218d ago

Thirty years without a cracked blade just means he's never pushed his heat treat hard enough to find out, not that the oil is any good. Motor oil is full of additives and dirt that do nothing for a blade, so I'll stick with canola and not hold my breath on his luck.