The exhaust on my Velocity pusher exits through the prop near the blade root (port on the right).  There is generally some grayish/dark discoloration on the prop after some flying. It wipes off with a little ‘Goof-Off’.

Just returned yesterday from about 1000 nm round trip.  After the outbound trip burning unleaded, there was some usual modest staining on the prop.  Coming back I was burning 100LL.  The prop then had fairly heavy brownish-yellow discoloration.  Is this due to the leaded fuel; or do I have to wonder weather there is something else going on?  It also comes off with GoofOff, but I don’t recall seeing this previously.

Al G