Thats it? just a 27mm nut? I'll give that a try next but so far it appears the oil is being cleaned out with every flush.
Is there anyway to pressure test the oil cooler?I'll have to give that a try.The first time after dumping the old coolant, there seemed to be more oil than coolant.I'm running just plain water through at the moment to determine if theres any oil in there and flushing it out... The water is coming out a brownish grey, almost a 'dusty' colour. If there was an oil leak from the block into one of the coolant passages, would there be 'blotches' of oil floating to the top of the resevoir, since oil and water do not mix?