Oil isn't the big problem. Talk with some engine builders and basically if you let a car sit for a decade it'll be fully oiled withing 1/2 second of operation. If you actually encounter this problem, the best thing to do is disconnect the ignition and crank the car a few times to build up oil pressure from the starter engaging the oil pump. If you have too thick of an oil for a given climate, then that's certainly going to be a problem. However, even my 15 year old toyota has 0w20 oil these days. The bigger problem in my mind is all the seals (like valve cover gaskets), belts, and the like. Especially, if you have a turbocharged car, you'll want to warm those seals up slowly before subjecting them to full operating pressure. Also, anyone who works on cars knows you can unplug a fuel pump and the car will idle for at least a few seconds just from the pressure in the line. Modern cars are essentially in a controlled stall when running at idle especially at operating temperature. If you idled a modern four cylinder for 5 minutes every day, I'd be surprised if you consumed an extra cup of gas over the course of a year. More gas likely gets spilled from those shitty new style gas containers than is consumed from idling during any given year.