Makes me think its oxidized. Can lithium grease do that? Sounds like it's just old, but it probably wouldn't affect the effectiveness much.
DISCLAIMER: I KNOW NOTHING ABOUT THIS. THIS IS AS MEANINGLESS AS MEANINGLESS SPECULATION CAN GET.
The McRip Effect (http://geekhack.org/showthread.php?23217-Announcing-the-LATEST-Ripster-Keyboard-Theorem-The-quot-McRip-Effect-quot-!).Show Image(http://geekhack.org/attachment.php?attachmentid=31850&d=1321025075)
I've since moved on to Fluoroinated PFTE.
(Attachment) 44915[/ATTACH] (Attachment) 44918[/ATTACH]
http://geekhack.org/showthread.php?22656-Gallons-of-Spooge-The-Official-Ripster-Lubricant-Experiment-Thread
Yes, pure lithium oxidizes immediately with contact with air.. Congratulations, good guess..
Although I don't believe this is the cause for the grease turning Brown...