NaymzJaymz

Vehicle in question is 2000 Civic with standard transmission and 253K(D16Y8). There is a reoccurring accumulation of black oil around the radiator cap, although the engine oil is clean and recent. The car easily passed the emission test here in California two weeks ago. It is throwing the erstwhile P0505 code, and performance is poor with jolty acceleration. This code was there before the smog test, but we cleared it and purged the cooling system and cleaned the throttle body(the oil on radiator cap was there all along). Is this(oil in coolant) the early stages of head gasket failure? There is not the slightest amount of overheating, and the car starts easily. We purchased the car with the high miles. The IAC looks brand new. We have not done any tests to check for head gasket failure yet. Thanks in advance for any help.