You can buy extra muffler bearing fluid from here. As well as some other 'harder to find' fluids.
http://kalecoauto.com/index.php?main_page=index&cPath=2
Also, don't forget to replace your 710 cap yearly along with those muffler bearings. You can find both on this page.
http://kalecoauto.com/index.php?main_page=index&cPath=3