Glenn

Quenching in old motor oil

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Besides health issues, motor oil is not the right quench speed for blade steels, at least.  Canola oil is cheap, non-toxic, and is a good quench for a variety of simple carbon steels such as 5160, 1084, and 80CrV2.  Pre-heat to around 120 degrees before quenching.

 

Don't use motor oil. Not worth the tiny amount of money saved vs. buying new canola, to have a less-than-ideal, carcinogen-laced quench. 

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Heck, I don't even buy Canola, I get it 5gl. at a time from the local super market deli. They change oil in their fryers weekly and happily fill a 5gl. gerry can if I ask nicely. Make sure it's clean and labeled with your phone number. Be sure to check back quickly you don't want them regretting the favor for tripping over the jug for too long. 

I was hoping for the donut oil but my shop smells like burritos, egg rolls, fish, french fries, etc, when I quench. could be worse.

Heck, a 5gl. jug of Canola isn't that much more than 5gl of cheap  motor oil and it wont poison you.

Frosty The Lucky.

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Iv used (used)motor oil once from a friends truck and the blade warped in very strange ways, like pretzeling, my assumption would be that the oils were mixed and had some other form of dex cool in there... Or that would be my guess.

Wasnt a good idea to begin with. 

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There's enough sulfur in cheap engine oil(and some expensive ones) that came out of the ground, to make a pretty good sulfuric acid for pickling steel.  Its the sulfur oxidation process from all the engine starts and stops that turns the sulfur into SO2, which in turn breaks down the oil, to grab some of its hydrogen, then more oxygen to make H2SO4, which ionizes with the aid of more acquired water from yet more broken hydrocarbon chains into sulfuric acid.  All that "Cracking" of hydrocarbons in your engine sump, is what turns the fresh oil black.  The metallic wear factor in engine bearings, camshafts, lifters, rockers and cranks in motor cars comes out to be maybe 3 grams, over the whole life of a well-maintained engine.  Dirt?  what dirt, how's it going to get into the engine sump?  Well, there are the situations of poor engine designs that let coolant into the cylinders.  That'll make dirt.

True synthetic motor oils are polymerized out of methane and ethane.  There are a couple of synthetic motor oils that don't have sulfur in them.  That's why they can last up to 50k miles.  Similar synthetic oils were invented by the Germans during WWII to run their aircraft and panzer tanks.

Maybe the best reason for using  some of the vegetable oils is their higher flashpoints.  Automatic Transmission fluids have much higher flashpoints yet, in the range of 600 to 800 degrees F.  In fact, after 10 years of rebuilding tranis, I've never seen the fluid actually combust.  Throw a lit match into it, and it just goes out.  And I've seen some tranis so abused the fluid in them congealed into solid varnish.  Of course there were the cases where the fluid came out stinking and black.  The trani clutch-pack plates in those cases were friction welded together, like a damascus nightmare.

It looks like most of the steel alloys are liquid-quenchable. So, which liquid(s) are best?  None of the motor oils mentioned had associated viscosity or weights attached to them.  Maybe multi-weight oils are better, if they actually increase in viscosity as they become super heated.

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Peanut oil has a substantially higher flash point than canola oil*,  That is one of the reasons that Chinese cooks use it when stir frying food in their woks.

A Chinese restaurant could be a good place to get spent peanut oil.

Vitamin  E  slows down oxidation of the oil..  I put a few capsules into the oil we buy for that reason.

SLAG.

* canola oil's "old" name was rape seed oil.

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Flash point isn't a factor in quenching blade steels all have critical temperatures well above the flash point of any oil I've heard of. Motor oil WILL work but the smoke is pretty toxic, consider it a Darwin Award hopeful quenchant. 

If you're concerned about the actual speed of the quenchant, you buy the oil with the properties you want. They've been listed once here look up the properties. 

Warping blades in the quench is NOT due to some imaginary differences in viscosity because it's used motor oil. It's operator error, you didn't know how to quench the blade. 

Frosty The Lucky.

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Having a blade come out of the quench as a pretzel isn't a bad thing.

If I mess up a blade that badly, I'm going to be hungry!

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4 hours ago, JHCC said:

  if I mess up a blade that badly, I'm going to be hungry!

Mr.  JHCC,

Wrote the above concerning quenched pretzel shaped knives.

The SLAG suggests that all is not lost. Said creation,  ("knife")  could be the start of a wonderful, creative work of art. (sculpture).

Daswulf and Ausfire  do wonders with bits of metal,  for their sculptures 

They are an inspiration,  for such matters.

SLAG.

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On 2/20/2019 at 6:51 PM, eutrophicated1 said:

after 10 years of rebuilding tranis, I've never seen the fluid actually combust

Ahhh...another tranny guy. 

We had a suburban in the shop once we were trying to get the job on through a warranty company. My boss said to drop the pan, put it back on, fire up the truck and let it run in reverse till it burnt up. After a bit of running fluid shot out of the dipstick tube hit the wall and burst into flame. 

Seen many a drum chucked in the scrap pile from being welded up. 

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