I've seen a number of crankcases with oil that looked like that... all caused by coolant in the oil. You may have bigger problems than you think.
If it is gas that seeped down the cylinder walls from sitting over time, it usually doesn't have the distinctive milky look, it just looks like watered down oil still, in my experience. When we bought my wife's Kaw EX500 it had an extra gallon of gas in the crankcase that seeped in from a leaky petcock and overflowing carb bowl. Looked like oil, did NOT smell like oil.