you are worrying too much about it, Your concern for such exact measurement is the reason there is a cool scale on the dipstick. Use that for the cold fill. Once you drive around and measure it between 70-85C - the dipstick would show correct on the hot scale.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)