Ok so heres something I’m confused about. Every video and guides tell you not to jack the vehicle up by placing the jack under the engine because there’s the oil pan and things like that.
But when you do a engine mount swap for example, why is it then fine to jack the engine up safely?
[Update: "> It’s not fine<." Sorry I misread your comment about swapping mounts. As I earlier noted below, that’s fine. But careful how you do it, else you may have a dented oil pan.]
When replacing an engine, chains are bolted to the engine using bolts and holes that can handle the load.
You can raise an engine by jacking it up if for small clearances, like to change a motor mount. How you do it is a judgement call. Sometimes it’s OK to place a jack under the oil pan. It’s usually better to spread the load with a board under the pan, or even better to find a lift point stronger than the oil pan.
The engine is resting on its mounts and if the mounts are unbolted the engine can be lifted free. Jacking under the engine with the mounts attached means the mounts will be supporting half the weight of the car and likely something will break.
Every video says you can place the jack WHERE? So ALL the videos say to jack under the oil pan? Nah. Don’t believe it. I always find a mounting boss on block and use that as jacking point. But I also have used a motor lift bar. Even used a cherry picker to lift motor. But that really bites when you are under motor where cherry pickers legs are.
You would think that would be obvious.
There’s a huge difference in the amount of weight between raising the engine a few inches with the weight of the rest of the car resting on jackstands or ramps as compared to raising the entire front half of the car off of the ground along with the engine.
I don’t think we’re all going to agree on this topic of discussions
I happen to think it’s sometimes okay to jack up an engine under the oil pan . . . with a piece of wood to spread out the load, as @JoeMario already pointed out . . . for purposes of replacing a motor mount
Another variable is the type of engine oil pan . . . stamped steel or aluminum
On some the engine oil pan is actually a structural component, and is much more than simply the oil pan. I’m not going to mention specific examples, because I’m sure you guys can think of a few yourself
I’d be more comfortable carefully raising the engine with such a setup, and that piece of wood, versus a plain jane stamped steel pan
But the bottom line is, I’ll find a way to get the job done . . . and SOMEBODY will always say “You’re doing it wrong”
But that’s life . . . no matter what we’re doing, somebody will ALWAYS say we’re doing it wrong
Perhaps some smart alec will speculate about all the oil pans, pickup tubes, etc. I must have damaged during the course of my career. You’re free to daydream, I suppose 
The engines that I most often lifted to work on were in domestic trucks with sheet metal pans and using a wooden block I have never damaged a pan. A Ford 460 engine must weight well over 700 pounds and I recall jacking up several for one reason or another…
Amen brother.
I have heard that more that a few times in this forum. 
You can jack up an engine as long as it’s not still bolted to the car or truck…Typically done to replace motor mounts…