I read recently that it is not a good idea to pull a winter storage car out of the garage several times mid winter to run at idle for 15 minutes (as I always have) because gasoline is pulled into the oil in the idling process.
New England winters
Following this logic to its conclusion results in this truth: Running the engine (anytime of year) contaminates your oil and causes frictional wear, both of which are always detrimental, so you should never run your engine. :)
It's has always been an old myth. To "warm up your engine" is really bad for it as it takes so much longer for the oil to heat up. Most engine wear happens within the first 5 minutes of start up.....So start her up and get going!!