Oil spots in the coolant are NOT normal.
I can't believe they told you that. Especially since you're not under warranty anymore... You'd think they would at least warn you about the history of headgasket problems and tell you what to watch out for.
It took a year and a half (maybe two years) for my headgasket to progress from an unknown problem to finally killing my engine.
Hold off on the Turbo. It will only accellerate the damage. If after flushing the coolant you noticed oil spots again, bite the bullet and get your engine torn down before you need a whole new shortblock like me.