On Sunday, February 12, 2017 at 6:15:09 PM UTC-5, Ned Simmons wrote:
On Sun, 12 Feb 2017 14:25:30 -0800, wrote:

To all the greasy folks here,
About 7 years ago I took apart my dividing head to make some changes.
I completely degreased all the parts. When re-assembling the thing I
used white lithium grease on all the parts that needed grease. Lately
the rotating parts have become very stiff, as if the brake was on. I
took it apart today and discovered that the white grease had turned
into green glue. But only on the steel worm and bronze worm gear. The
all steel tapered roller bearings at both ends still have grease that
works and looks like grease is supposed to. It appears that there is
some kind of chemical reaction happening between the grease and the
bronze gear. Anybody here know anything about this?
Thanks,
Eric

Some sulfur containing EP additives are not compatible with copper
bearing alloys. It's a common concern with gear oils. I've never heard
of an issue with grease, but if the grease was made from oil with
non-compatible additives...

--
Ned Simmons

This reminds me of a warning in a repair manual for old Jaguars, at least the early, 6-cyl. E-type: They had bronze ring gears and they had a note about which lubricants were compatible and incompatible.

My '57 Alfa Romeo Guilietta had a bronze distributor drive gear. I don't remember any specific warnings, but they were explicit about oil grades, including all of the letter designations that came after the weight.

(In '58, Alfa switched to steel gears.)

--
Ed Huntress