The mileage tests on those sales stickers have start stops to show “urban cycles”, so the companies cheat by start-stopping the engines. Then sticking us with the stupidity.
In no engineering world does it make sense to do that to engines, but, the companies simply don’t care.
Then you have the dumbest in humanity adding to engine destruction by blasting the engine at start-up. As a car guy, I cringe when I hear that. One of my in-law does that and I tried to explain the damage he is doing to the engine….he dismisses it, his explanation is the harder you rev it, the faster it warms up, therefore less wear. Vroom-vroom voodoo idiocy.
Engines need oil pressure and volume for the bearing surfaces. The problem with cold starts is that the oil is so viscous, that even though the pressure is sky high, it does not flow fast enough through the oil passages, thus starving the bearing surfaces. That is why some have gone to synthetic and 0 weight. The lower the weight, the faster the oil flows in cold weather.
Remember the days of 20w40 summers and 10w30 summer oil? Gone. With synthetics, they resist shearing off far better and they don’t break down as quickly in higher summer temperatures so now we have 0W20 or 0W30 all year round.
How long one warms up the engine depends. In a modern car, in summer, on a flat driveway, through suburban roads, slow acceleration for a few minutes, ten seconds are enough. As long as there is no high rpms needed to overcome some obstacle or merge into speeding traffic. As the temperature drops, the need to warming up increases. If there are obstacles, like going through snow, uphill driveway, need to merge into fast moving traffic, then the time keeps rising and rising.
I can see 5-6 minutes for 0.F merging into moving city traffic. Worse case for the car engine/drivetrain is to jump into highway speeds. Consider an engine block heater and votive candles to the Car Gods. At minus 20 Minnesota winter…a good bon fire. Lol
In my area, at O.F, unless there is snow on the ground, one is idling out and practicaly idling/puttering through multiple blocks of slow suburban stop-go before encountering moderate speed main roads. Ideal, low stress start-up driving. A minute is enough.
How long one takes is a calculated decision that separates a good driver from an appliance jockey.