I would say it is normal carbon build up but others might say differently. No need to change tranny fluid but it won't hurt either. Duncan. On May 5, 2012, at 3:46 PM, Julie <julie.hey.ho.lets.go@xxxxxxxxx> wrote: > I replaced the tranny in my '71 a few 1000 miles ago with a freshly rebuilt > one. > > Is it a good idea to change the tranny oil now that it has some breaking in > miles on it? > > If yes, is one brand of 80-90 weight oil better than another? > > When I took the distributor cap off on top of the middle of the rotor and on > the little metal post that is inside the middle of the cap where black and > gritty? What is that about? It was not like this when I switched the > electronic ignition on the side of the road a few weeks ago. The Bus seems > to be running fine. > > Julie > > >