I ran it just enough this a.m. to warm it up and verify that the float was unstuck then did the oil/filter. Sure enough, thin and stunk like gas (actually measured the used oil and probably had about 1/2 pint of gas in it). I guess my crankcase has been flushed. Drained some more gas at the petcock and topped it off, so I should have a fairly "normal" seafoam/gas mix now.