Say the outside temperature is 20 deg. f and the drive to work is only 5 miles. Should your vehicle idle for 20 minutes until your oil temps. are normal or should you just drive the 5 miles and get what oil temps the short trip will provide. We know the longer a vehicle will idle the greater contamination of fuel and blow by which leads to increased wear. And the other edge of the problem just firing the thing up and taking off for only five miles will not get you anything but high condensation and high iron levels. That is my daily problem in the winter when it is very cold. It is not realistic to drive 50 miles just to achieve normal oil temperatures but then again everyone wants to take care of their engine. Short of a block heater or a oil heater what should a person do? Change oil every month or what?