I use a copper based grease in my centre, BUT, it is a torsen type diff.
http://www.helgerracing.com/j16fioro...lodedpage.html
Awesome diff for truggy/buggy applications.
Losi SCTE SC4 Pro 4000kv, Tekin RX8, 2S
MP7.5 Kanai III Tekno Neu 1515/2.5D 1700kv MM 4S
LST 2 Carbon CC 1717 1Y 1580kv MM 6S
Futaba 3PKS Spektrum Pro