see my dad has a 1.5L civic D15B7 engine, it has done 350,000ks he always lets it warm up and drives good with it the car has never had any problems exept the usual servicng and changing parts as they have done alot of ks - example, water pump, hoses, etc. i thought its known for less internal engine wear if you warm up due to letting the oil warm up while idling instead of driving cold and the oil is still not warmed up to lubricate the internals properly. i always let it warm up a quarter of the temperature then drive off