90 Weight Gear Oil Damaging Brass and Bronze?

Someone in the Yahoo 4x6 bandsaw group said they know for a fact that automotive type 90 weight gear lube will attack brass and bronze if
used in machine tools. Has anyone heard of such a thing? I was going to use Mobil 1 EP Hypoid Gear Oil (SAE 140) in my Clausing 8540.
Thanks, Steve
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snipped-for-privacy@aol.com wrote:

I used it for years in a hydraulic bandsaw downfeed until I found out it is only about as viscous as 30 weight motor oil. The downfeed was made entirely of brass parts, which suffered no ill effects from the exposure. I think the yahoo guy was fullovit.
GWE
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I have a 1954 Stokes Oscillating Granulator with bronze bushing bearings on the rotor. They are continually bathed in 90W high-sulfur oil. The oil sump also contains a 100% brass oil pump, and numerous brass oil line fittings.
If anything, it would be the sulfur content that _might_ damage copper-bearing materials.
Remember, 1954. No damage whatsoever. In fact, except for 1/2" of sludge in the sump, it looks like a new machine (inside<G>).
LLoyd
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I don't know the Clausing, but unless you have hypoid gears, I can't see how you'd need (or want) to use a hypoid oil.
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snipped-for-privacy@aol.com says...

*Some* EP additves will damage *some* copper bases alloy. Most EP gear oils are no problem - Mobilgear is one that I know is OK. Does your mill really call for an EP oil? The gears in most machine tools are not loaded heavily enough to require it.
Mobil has very good tech data on their lubricants online if you want to check the Mobil 1 to be sure.
Ned Simmons
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On 29 Mar 2006 21:49:26 -0800, " snipped-for-privacy@aol.com"

some of the friction modifiers work by bonding with the zinc in the alloy. when the lubrication film breaks down this oxide is scrubbed off providing a last ditched lubricating action.
I used castrol gtx motor oil on my lathe until I discovered all the brass oilers going red. the explanation was surface leaching of the zinc component in the brass alloy leaving a red copper surface.
for my lathe I now use shell tellus 46 which is a transmission oil. this oil glues to lathe slideways quite nicely and doesnt leach the brass. yeah I know the clausing isnt a lathe.
(australian experience) Stealth Pilot
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When I was researching oil for my Van Norman the presence of "yellow metal" in the gear box ruled out a few choices, according to Mobil's tech support.
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Mike what oils did they rule out? I just picked up a Rockwell Mill and the horizontal gear box calls for 140 weight EP gear grease. Local store was a bit confused.

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