Apparently the oil in the coolant reservoir is caused by a leak in engine head. Whether is the gasket or a cracked head I'm still not sure of. However I've been told that is likely that the components in the lower part of engine having compromised buy the low oil viscosity caused by the mix with coolant. I estimated the repair cost but it really looks like I need to buy a used we're refurbished engine. But, it looks like there is a class action lawsuit against BMW/Mini having to do which the oil pump seals. The oil pan gasket has been repaired twice on my vehicle. And that was when the car had less than 70,000 miles on.