Something leaking from #5 exhaust gasket

[overshot]

I seem to have something leaking from the #5 exhaust gasket. I would assume that it is oil. I can't really tell, it doesn't seem to have an odor. And since I work in a lot of dusty areas it collects a lot of dirt around it. It started leaking about a month ago, when the outside temp started staying hot. It's a 2250 with 526000 on it.
Do I need a new head? I hope not. Any advice will be appreciated