Steel Soldiers now has a few new forums, read more about it at: New Munitions Forums!
Microsoft MSN, Live, Hotmail, Outlook email users may not be receiving emails. We are working to resolve this issue. Please add support@steelsoldiers.com to your trusted contacts.
Sounds like plain old slobber.
MF engines don't like being idled, or run under temperature for long periods of time. If you idle a lot, any place your exhaust system has a tiny insignificant leak, it will ooze black sooty slobber.
The way you can tell the difference between slobber and oil...