I did replace the coolant and transmission thermostats and the glow plugs. I had to replace #1 glow plug again due it failing. BMW replaced the part free of charge. Looks like the EGR cooler may be next on the list.

Coolant temperature stays above 85C even in -10C air temperature. It's easily increased the minimums by 5C and it does reach 89C+ now. Fuel efficiency hasn't changed much, maybe a few tenths but it's within my normal variance, 26+ mixed, so I'm not going to say that it's really made a difference.

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8/2011 X5 xDrive35d Sport, Black Sapphire Metallic, Black Nevada Leather, Fine Burr Walnut Trim
2/2001 M5, Jet Black, Exclusive Complete Black Walk Nappa Point Heritage Leather, Black Cubic Trim