I have an untouched stock 80 cu in Evo with 90,000 miles on it. After a long trip I noticed oil on the cooling fins below the head gasket.I cleaned the area with brakeclean and after about 300 miles no more oil has appeared. I am being told that I could have a cracked head or barrel and the engine needs to get realy hot for it to leak. Is this common and how do I tell if I have a crack? I don't want to go to the expense of fixing head gaskets and still have a problem as I have a chance at a totally rebuilt engine with warranty for more cost of course - advice please