"Grant Erwin" wrote in message
...
wrote:
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


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

It is likely true that an EP gear oil will attack copper based components in
machinery. EP mineral oils with a rating of GL-5 have this characteristic,
which is a powerful oxidising additive to create a scuff resistant surface
on gear teeth. It is normally used in automotive hypoid differentials and
some manual transmissions designed without vunerable copper alloy parts. The
effect is not dependent on viscosity.

To avoid the problem, a gear oil with a rating of GL-4 or less should be
used. Avoid high EP ratings

The equivalent viscosity to SAE-90 gear oil is SAE-50 in engine oil, ie ISO
VG-220.
--
Regards,

Chas.

(To email me replace 'xxx' with tango papa golf)