Yes, the oil will cool the lines and that means the lines are heating the oil flowing through. Not good. Newtis (in turbocharger faults) states explicitly, many times, that with any turbo replacement the supply lines should be replaced and return line thoroughly cleaned. Upon turbo fault, the lines are the first suspect. That’s clear direction to the dealer network to mitigate burning up new turbos at dealer & BMW expense. If that’s not a sign of “CYA”, I’ll crap a bigger turbo.
All this adds up to room for improvement. I’ve gotta do them (well, 1 of them) so I might as well give it a shot.
To insulate or not? Another method for heat? Extra joints in each line to make them serviceable, or no extra joints to eliminate potential failure points?

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- Tom
‘10 E70 diesel, hud, hot/cold weather, 3rd row.