my 95 sl has 280k miles on it. last sunday i went to town,noticed the temp was almost in the red.on inspection the coolant resivior was ozing a brown gunk-oil in coolant.there was no loss of compresion,i even started her up to get in driveway when the tow truck brought me home.ran like a champ.i pulled the head and can find no evidence of gasket failure the only place it leaked is from the coolant res i can find no cracks and there is no water in the oil...what happened???

cracked head