I have a new 2019 F150 with the 5.0 engine. I saw this in the manual.
What is the reason behind this? I don't really want to sit inside my garage for 3 to 5 minutes with the engine running.

 

I believe that it is referring to if you start it up without going anywhere and shut it off. If you have been driving, it's fine. I wouldn't really worry about it either way, though

I am sure it has to do with oil circulation, and maybe battery charging. (to a lesser degree)

 

Are you sure that language in the manual isn't intended for the diesel engine?

 

This would really only apply to turbo cars, especially after a hard run to allow the turbos to cool to lower temperatures, and avoid coking the oil if dino oil is used. On the other hand, the Stop Start will turn it off for you regardless, turbo health be damned. Just saying.

 

Only really need about 10 seconds after running 'er hard before shutting down on the turbo trucks. Let the oil circulate a bit to take the some residual heat out of 'em.

 

There's already been discussion ad nauseam about this on the Forum, and it's unclear if it refers to only diesels because of how the manual is laid out.

There would be a good reason on the Ecoboosts to let the engine idle for at least a minute before shutting down to prevent oil coking in the turbos, but since they're water-cooled as well, that's not a problem.

So the argument goes on.