In reference to these EGR coolers going out, a friend of mine has a 2008 F450 with a 6.4 in it. He had it to a local dealership several times and of course they said it was fine, well about 3 hours out it started blowing white smoke out the exhaust and the dealership there has agreed to put a new EGR cooler in it but I'm wondering about the overall health of the motor and the life left in it. If it's been burning coolant for this long, an oil sample seems like a good start, any other suggestions?