Agree it may be rare, but it did happen. Maybe I should submit it to Ripley Believe it or Not? I had posted about this a while back (see here: Can coolant mix wth oil inside the turbo?) and ksw92_mk2 offered an explanation in that there could be a leak between the oil and water chambers of the turbo. Since the coolant pressure in the turbo is much higher than the oil pressure at the side where the oil side drains into the oil pan (essentially atmospheric pressure), coolant could force itself into the oil passage (but hardly the other way around) and coolant ends-up in the oil pan but. Made sense to me. And, my problem disappeared as soon as I replaced the turbo. Coolant pressure after turbo swap held just fine.