I thought that the arguement against idleing a modern diesel (even a gasser) for longer than necessary was this:
Motor oil works more efficienctly/better at operating temp. Starting the car and idling it for 20 minutes means the engine spends more time running with its oil at less than optimum temperature. This extra running at low oil temps accelerates wear on components that need the oil to be at operating temp (valve guides? oil seals ?)
Obviously, gunning the engine to warm it up quicker is not a better option, and the best compromise is to start it right before you plan on driving away, and drive away slowly to minimize stress.

I cant argue the factuality of this argument (I know my nuclear submarine keeps its oil at a certain temp at **all** times when something is spinning that needs it - not a good comparason other than the fact the shipboard reduction gears are regularly re-used from one ship to another (each ship averages a 20 to 40 year lifespan...)

I can say that having a warm car to get into on winter mornings is more important than the slight wear that this may introduce.

I also am open to more scientific/proven arguements.

-John

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2009 Kia Sedona
2009 Honda Odyssey EX-L
12006 Jetta Pumpe Duse
(insert Mercedes here)

Husband, Father, sometimes friend =)

Block heaters work great, but they have to be plugged in to work.

__________________
1999 E300DT (131,800) 154,000 Black on Black SOLD

2006 CLK 500 coupe Capri Blue on Grey (zoom,zoom)
47,000mi

04 VW TDI Passat 80,000mi
(Techno)

How to eliminate oil dependency through market-driven approaches.
“We could cut oil use in half by 2025, and by 2040, oil use could be zero,”
The Sound of Diesel Speed
Ode to MB

Just one more reason for me to justify that grand on the espar.

http://www.espar.com/htm/Specs/water/D4Wspec.htm

I may get foolish and do it one day when I have a little extra in my pocket.

JP