Originally Posted by RCFVR
That is usually the result of aluminum/aluminum rubbing. Check your header mount with the engine to see if there is some abrasion going on there. Assuming the engine has been run in already? A new engine might produce this as the parts are wearing in, initially.
Thanks for the reply.
If it were "aluminum/aluminum rubbing " wouldn't there be silvery flecks of alloy in the oil
It's not a new engine but in good condion and certainly no-where near worn out.