The son driving it will play no part in the decision. If young age was a case for warranty denial then this would be posted all over the place on the internet. Without hard proof making random speculations based on nothing other than all young drivers race all the time won't go very far at all. The mfg has to have some solid evidence if they want to win a case in an arbitration or in a court room. They know this. They will have to have SOMETHING to go on. Pictures of a sludged engine, lack of maintenance receipts or some kind of previous history of some kind of event. And even then, it's a tough sell for them.
They can make things tough for you, making you wait a long time and go through the processes, and that in and of itself is something some people just can't afford if it's their only car. I was lucky that I had another car and could wait it out. In my case they tried to say there wasn't a "defect" in the part... they didn't even try the slippery slope of "abuse" or neglect as they probably knew it's impossible to prove if the customer has receipts. They can't prove you didn't change the oil, but you have proven you bought it. Why would a reasonable person assume you bought oil but didn't use it? The "defect" defense is almost as shallow. They are saying there was nothing wrong with it therefore it shouldn't have failed, therefore the user must have done something wrong. Except that is full of holes too. It failed for whatever reason, whether there was an initial defect or not. This is what a warranty is for. The arbitrator didn't even comment on a supposed defect. Just said the car's under warranty, you have proved nothing whatsoever, you have 30 days to fix it.
I shoud say, that is all worst case scenario. I really don't see any issues for you at all. I think they will fix it without issue. You just have to let the process take place. They will appeal the mfg for a teardown and inspection most likely (though I know on some items even this is left up to the dealer to pick and chose which ones they do this on). Maybe on such a high ticket warranty item like engines they have to, I don't know, but something like a transmission could be left up to the dealer. Either way, you will no doubt have a nice clean engine and oil/filter receipts... pretty cut and dry. They will more than likely order you a longblock relatively quickly and put it in.
My advice is to be polite and courteous and understanding but firm in your resolve for them to fix it free of charge. The dealer can be your friend or make things long and drawn out. They have no personal interest in this unless you give them one. Good or bad. I advise to give them a good one to speed things up.
