Dino and sync oils don't break down, it's the additives breaking down with debris collected over time. This includes collected moisture. So if you ran it 5k per year and changed it out at 15k, there shouldn't be an issue. But here's the problem. While under warrantee, if the manufacture wants to, they can state that you were warned of the recommended mileage / time frame and not warrantee you engine if you didn't meet there recommendations. Unless you sent in samples and paid for analysis every 6 months proving your oil is still within all recommended specs. And that is a hassle and at least $35 each sample. And any oil / filter changes made to the vehicle not by dealership, must be proven if they requested proof. So you better have receipts.
I hate having to waste money on something that is really unwanted or unneeded, but 'you threw out one big pile of cash for that vehicle'. Is it worth saving a few dollars and hoping it doesn't have engine issues and not needing the dealership covering it ? GIVING THEM the choice if they want to cover or not ? And oil change it what, $100.00 for oil and filter ? I throw that in my fuel tank and more each fill up. How long is your warrantee, standard 36 months ? Extended ?
For my old '06, I went to the dealer twice during the warrantee. Once for a recall on the steering (like so many other had) and once for the heater door falling from improver installation. They covered. BUT it didn't have, (nor ever had) engine issues and they didn't need to check or ask for proof of service.
Odds are, you'll be fine. But do you gamble any ?