Why does oil weap or sweat out of grease?

[greenjoytj]

I have some Lucas Red-n-Tacky that I noticed liquid oil separating out and floating on top of the thick grease. I checked a tub of Rand brand "Hawg" gun grease and it also has a big puddle of liquid oil floating on top. I think the Rand Hawg grease is re-package Lucas Red-n-Tacky it looks, smells feels the same.
My old tub of molly grease has not separated but I've ruined too clothes to mess with molly grease any more.

Have these greases gone bad?
Will the lighter oil keep sweating out till the grease is a hard lump?

[M-Tecs]

http://www.machinerylubrication.com/Read/28761/storing-grease-to-avoid-bleed-separation-

http://www.machinerylubrication.com/Read/28517/grease-dry-out-causes

http://www.maintenancetechnology.com/2009/07/grease-basics/

[country gent]

most greases are a wax or clay base carrying the lubricants and holding them where they need to be. Like oil on a piece of metals slowly flows ands moves the oil in grease over time does the same. The carriers are heavier so the oil works to the top. Ussually it can be stirred back into the mix.

[runfiverun]

most greases are mineral oil based.
some clays can be used as a gelling agent to augment the stearate used to gel the oils into a grease.
usually it's a lithium stearate grease but there are other stearates you can use and even different Lithium stearates. [longer or shorter lithium chains]
aluminum, calcium, and sodium are all different stearates used to make a grease.
they can have other things like the clay used as a gallant and sometimes even strong chained waxes are used to add more strength to resist pounding or high pressure [load bearing] situations.

greases run the gamut of looking like a thin oil up through it looking like a block of wax.
and are graded from OO up through about 7. [7 is like 12% stearate content and usually has a supplemental gallant agent]
your average chassis grease is a number-2 [about 3% stearate content] white lithium is a number-1.
wheel bearing greases are a 2.5 or a 3.

anyway they all will give up some of their oil content [more or less depending on how/where they are stored]
it isn't of any concern just stir it back in or dump it off.