Should both petrol and diesel turbo engines be idled after use?

Further to your advice on turbo cooling by idling the engine for some time after use, is the advice equally true for diesel and petrol engines? I have a 2-litre diesel BMW and, in normal driving, it is pretty rare to go above 2000rpm and in cruising mode at 70mph, is well below. Even at 80mph it does not touch the 2000 level. Is it still sensible to idle for a couple of minutes if stopping immediately after a long stretch on a fast road?
Stopping for fuel on the motorway, yes. After a long ascent, yes. After towing, yes. Normally pottering around a town at the end of a journey does the job. But the most common place to coke up a turbo's oilways is when stopping for fuel on a motorway. Just give it 30 seconds at idle once you reach the pumps before switching off.

Turbos on petrol engines are usually watercooled whilst diesels simply rely for cooling on the oil being pumped through their bearings.
Answered by Honest John on

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