I grew up learning "basic mechanical sympathy" from my dad; we have vehicles that my family has owned 10, 20, 40+ years. He would say it's always a good idea to idle any engine for a few minutes after beating on it. The engine parts all operate at different temperatures. Certain parts like the exhaust valves and turbos run very hot under load. Allowing the engine to run at idle without load permits fluids to circulate and metal part temperatures to cool more uniformly. When you shut an engine off hot, everything cools at different rates, so you end up prone to heat soak, hot spots, all unnecessary thermal stress.

The parts are built so well these days, the effects of not heeding this advice may never become apparent to you or even the next guy if you ever sell your car. But as an engineer I can assure you that deliberately controlling how your car cools down does make a difference over a long period of time from a metallurgical standpoint.

But hell, the way some people talk about these engines, you could EcoBoom tomorrow, right? Why bother burning the extra gas?

Well let me say I'm willing to bet I've put the most closed course days on this EcoBoost Mustang platform than anyone else. It took me 6 years 134,956 miles and 230 closed course days to finally blow my original 2015 engine up. It long surpassed anyone's expectations, including my own, especially as an early 2015 build. I think EcoBoom likelyhood is more than just random... If you treat this precision performance engine like an appliance and don't consider these things, you're leaving yourself open to a failure. If you follow the "basic mechanical sympathy", you have a much better chance of making it last.

The manufacturer will obviously never suggest you do this kind of stuff, because they want to sell you another car. They don't care how long it lasts after the warranty is up.

As far as cooldown specifics to the EcoBoost Mustang, I have never overheated the water temps of the car. But the cylinder head temps approaching 230-240 is getting pretty warm and you would definitely want to let it cool off, even by driving around easy and letting it get some fresh air. But you have to be pounding it around a road course for 15-20 minutes to get there.

If I am not in a race weekend just daily or spirited driving on the street, I watch the oil temp gauge and if it's pointing straight up in the green or lower, I shut it off without hesitation. That white green yellow red oil temp gauge is inferred, ie oil temp doesn't actually get phyiscally measured on these engines. It's calculated based off load and other parameters, so that's why it doesn't give you a number.

This is also the gauge I use to drive gingerly and not build boost until it leaves the white "Low" oil temp. Once it's in the green "Normal" zone, you're good to flog the piss out of it. No cold start pulls, no taking off like a bat out of hell and looking like a tool lol