I highly recommend the chrisfix videos, btw. We've both learned a lot about cars.
Thankfully, he watches kurzgesagt, BackYard Scientist, VSauce, TED and mostly scientific or programming videos so its mostly 5 to 1 , educational to entertainment videos with the limited screen time he has.
The Khan Academy courses are really good as well as the ProdigyGame (for math) for keeping him engaged and multiple grades ahead of his current grade.
Clean language, strong work ethics. Works with heavy equipment, builds a Castle out of Shipping Containers, fixes trucks/boats/bikes/excavators etc.
Mustie1 is another clean educational YTber with similar content: https://www.youtube.com/user/mustie1/videos
To be fair I do this and I'm 34. ;)
Although you should tell him that running is the worst thing for gainz.