Brakefluid-safe lubricant, what is this stuff? Options

[enderswift]

hey there,

I decided to take apart my old clutch hydralic components to see exactly that failed inside of them, to help me diagnose why my new clutch components are giving out. When i took my old slave cylinder apart, it had a grove on the whole piston assembly that held a little bit of white grease. When I saw this I raised an eyebrow because everything i've ever learned says that brake fluid and petroleum dont get along. I cleaned the grease out and put the slave back together to see what would happen. Well it definately doesnt compress as smooth as before, so the grease obviously serves a purpose. That leads me to the question, what is this stuff? its definately not something made of oil because that would just ruin the rubber seals, and a google search hasn't turned up any hits for lithium grease... any ideas?

pics can be provided if necessary, though i hate busting that camera out..