Here is the heart of the problem-the 6.0L Power Stroke's factory engine oil cooler has small passages that can clog, reducing flow and limiting the amount of heat transfer from the oil to the coolant. If coolant can't pass through the oil cooler, it can't get to the EGR cooler, which can then rupture. According to BPD, the best way to test an engine oil cooler is to measure the temperature of the engine oil and coolant at the same time. When the engine oil cooler is working, the coolant and the oil temperature should correspond closely-within 5 degrees at idle. It's not advised to run your 6.0L if you have a leaking EGR cooler.