IIRC, it's just a silicone grease. Silicone grease is often used to lube o-rings because unlike petroleum based grease, it won't attack the rubber. Has lots of other uses too.
You can get a tube of silicone grease for under $5 from NAPA.
see:
http://www.super-lube.com/silicone-lubricating-grease-ez-53.htm