Posts: 41
Score: 100
Joined: 6/30/2002
Last Login: 2/16/2013
From: Middletown, CT, USA
Status: offline I agree with everything that has been posted here. One other thing I would look for is a loose bolt holding the engine down, at the muffler, or anywhere else in the engine area. If a bolt is vibrating even a little, or the muffler is loose, the vibrating turns the oil very dark and looks like this. I know, I've seen it on my models...
Worth a look..
I am pretty sure this is much more on track than a problem with the oil mixture or carb settings. The other thing is to test the engine (while stopped) around TDC for some looseness or a popping feel in the rod end. The last time I got a mess like that, the engine ate a jug.
YMMV