tamiya has a product called Tamiya Sliding Damper grease . package contains three small tubs, hard(purple), med.(blue) soft (green) avail at your LHS
l
the stuff looks like colored silicone grease with the feel of say peanut butter, weird stuff , works wonders.
works great with xmod friction dampers (shocks)
put a tiny dab on end put together and bam! takes the bounce out of them. have used this stuff on larger scale friction dampers
my xmods - med. springs ,soft (blue) grease
hope this helps
btw i wouldnt use "normal" grease or a silicone type...it tends to break down quick