well, I've used motor oil for years and not had any problems.
in fact I have 20-50 amsoil synthetic in my oiler cans, and in my way One-Shot. and in all my mills moving parts. Just cause my dirt bike didn't like it and I wanted to get some use out of it. now I find my street bike likes it.
I finally bought some air tool oil last year. Well, its slick too.
As I posted under the lubrication for South Bend Lathe topic, There are paraffins in motor oils.
In refrigeration machinery, air tools and firearms where temperatures can be depressed by expansion of gasses or in the case of firearms, by taking them out in the cold, the paraffins will go to a waxy solid and gum up the works.
desergison's synthetic is paraffin-free and the light hydraulic oils are pretty much so. The Marvel Mystery oil has such a strong solvent in it that it will free up anything.
Home shop and light industrial users can get away with more than construction users. The heavy duty rock drills can get the exit air stream so cold that it throws ice chunks.
That brings up another point. Air tool oil not only has to stay oily at low temperatures, but it can't go to snot when mixed with carryover water in the air. I, sadly, have had to de snot several pneumatic systems and it 'snot fun.
I use Relton Air-Flo air tool oil in my tools. The bottle says it contains PTFE.
I don't know where this bottle came from, probably bought from one of the tool houses.
I run a light spindle oil in my FRL's on the presses. They all are equipped with Ross control valves which specifically state to not use air tool oil. They even state do not use marvel or those types. They contain something that will destroy the Buna seals in the valves.
Air Tool Oil tale:
Many years ago when I was selling tools to mechanics, there was one that was using diesel fuel as an air tool oil. He kept sending in his 1" Air Impact wrench for repair because the anvil kept breaking. No one could figure out why until he told what he was using as lubricant. Seems the diesel fuel was detonating as if it were in a diesel engine due the the air pressures used with a resulting extra power kick that would break the anvil. He stopped using diesel fuel and the problem was solved.
Marvel Mystery oil was originally intended for "top cylinder lubrication" in internal combution engines.
The Marvel Mystery Oiler fit on the intake manifold and there was a valve that allowed the oil to enter the partial vacuum in a metered amount.
The purpose was to lubricate the intake valve guide (the exhause valve guide might have got some by the carry over during valve overlap).
Of course the piston rings and cylinder wall got their share.
The stuff has to have a strong solvent to cut the lubricaing oil and carbon deposits that caused sticky valves.
It also had to be able to stand high temperatures and still lubricate.
and Most Importantly, the Marvel Mystery Oil had to be combustible without itself leaving a gummy deposit.
Tremendous advances in crankcase oil chemistry and positive crankcase ventilation have made this set up un necesary. But Marvel lives on.
Besides, the EPA and Californis's CARB would blow a fuse if anyone suggested metering oil into the intake of an engine these days.
The upshot of the matter is that any oil that can put up with going through a hot engine is certainly not what one might want to breathe.
In addition, the exit air stream of an air tool using Mystery Oil is falmmable. There would be more horror stories if the exit air stream wasn't so cold.
Rotary air tools are straight expansion engines, however the reciprocating tools, anything from chipping hammers to rock drills, can have compression during part of their strke. Light, flammable oils can "Diesel" when the air that carries them is suddenly compressed.
Marvel also makes an air tool oil. I usually use Dextron myself. Air tool oil we use at work says it's a straight mineral oil, breathing fumes won't hurt you but it might relieve constipation.
I heard the story that way back when during WW1 the airplanes were 2 strokers, and they used caster oil for lube. Lack of constipation was a problem for those around the smoke of these planes, or so I've heard.
Marvel Mystery oil is still commonly used around small recip aircraft engines. I always put a qt. in the 10 qt sump when I still owned a Cessna 175. Great airplane, and as my surprised mechanic noted one day when he decided to take it out by himself after an annual, "That thing runs like an electric motor!"
He got it on a good day, though. The GO-300 horizontally opposed 6cyl 300cid motor, with gear drive reducing 4:3 to the prop (3200 motor to 2400 rpm prop) was aerodynamically efficient with the oversized 84" fan turning so slowly, and the motor seemed to rev into a "sweet spot" somewhere just past 3100rpm. But it resulted in high cyclinder head temperatures....and frequent sticky exhaust valves. Especially over water! Not sure how much the MM helped, but maybe it would have been even worse without....
Darn, you mean you actually have to oil those things? Just kidding. One time I had a die-grinder that stopped and I had to oil it. WD-40. Other than that I've never oiled any of the others that I use. I think the Energizer Bunny must have pissed in them.
Sorry, Jim. I've used air tools around red hot work at times all my life and never had a "poot" from the exhaust stream as a result of a nearby ignition source.
I can't buy flammibility of an air tools's exhaust no matter how carelessly it was over-oiled because I've done it to purge a water slug. While the oily exhaust smoked furiously when it hit a red hot forging cooling on the floor for example there was no flame and certainly no ball of fire traveling up the remote exhaust to grenade the air tool in the user's hand.
There's a little matter of flammiblility limits.
[This message has been edited by Forrest Addy (edited 10-30-2003).]
If you are using the airtools in a shop where cars are being refinished, you have to be careful to chose a lubricant that does not contain silicone. Silicone contamination in an autobody shop is serious business. It can cost thou$ands in profits before the mess is completly isolated and cleaned up.
I heard a story once of a disgruntled employee adding a pint of ArmourAll to the air compressor crankcase. It took them weeks before they were able to paint a car again. Everything in the shop was covered in a fine mist of silicone.