Kids are incredible, one thing I admire the most is their resilience, in this case he certainly took some initiative, probably wanted to help and fix the car, was confident because the experience with his dad, learning unintentionally how a spray can works, how to clean up, I have to wonder, were there any runs LOL ! Thats almost priceless, I cannot imagine either of your reactions had you seen him do it, I'd want to be angry, but something like that, I'd have wanted to ask him about it nicely, and listen to what he says, then figure a good way to tell him his intentions were good, has heart of gold, but there probably is a better way to repair LOL !
It reminds me of being not much older, 5 or 6, and I was home ill, not in school, no one home either. I wanted some chocolate chip cookies, well I wanted to surprise mom more than I wanted the cookies, I had watched or helped bake them before, but had recently just learned to read. Don't you know I made the darned things, followed the recipe, knew how to set the stove, and they came out pretty good 'cept one minor problem, I missed one thing on the recipe, amount of salt I misread or mis-understood, just a tad too much, I was close but just enough that you could taste it a littlem they were still good, soft and all that. To this day, I cannot grasp how I was able to do it, never got punished, I mean how do you punish a kid for having a good heart, LOL ! Most of my life followed suit, the parental units were really not around that much for me, if you wanted something, you did it yourself. I would have been a lot smarter then if they were around, and though a late bloomer, having to figure things out on my own, I still look back and realize how seemingly unintelligent(dummy) I was with some things, things my parents never participated in or things I did not do with them mostly. I drove a tractor at a young age but was clueless on other things kids learned throughout their youth.
What you are doing with your dedication to family and especially the younger members, like the children, teens, is priceless, which I am positive you don't need to be told, I say it to reiterate and in admiration of those who go the extra mile for their kids and help them along the path that leads to success regardless of what they do. I learned a lot from my parents, mostly about what NOT to do LOL !! I laugh now after all these years, thankful for how ever I made it so far without too much trouble, could have been a lot worse LOL !