You should see actually how little warranty covers its, ridiculous. Even more so the extended warranty. Anything mechanical that goes after 5 years will come out of your pocket.
Actually what you've stated is incorrect, at least for the US and Canada. The extended 10year/100K/120KM bumper to bumper warranty covers everything except the bumpers, including oil changes. They will do a comprehensive valve cleaning at 65K with this warranty. You can also have it done chemically with this service;
https://www.bgprod.com/services/gasoline-fuel-services/platinum-fuel-system-service/ It's is also warranted by the manufacture.
Also the 10/100K powertrain warranty will cover the engine replacement in its entirety.
BG Products do a great job of cleaning intake and exhaust valves, especially along with their engine services. They have a direct system that cleans and service the entire system including duel rail;
https://www.bgprod.com/services/gasoline-fuel-services/gdi-fuelair-induction/
They offer many engine cleaning services which will keep the engine and powertrain in peak condition
Oil dilution is a problem with any GDI from any manufacturer but the Veloster N has Oil/Fuel dilution of less than 1.0% which is a trace. You can verify it by sending a sample of your oil to any Oil testing lab. Make sure you let them know to check for
Fuel Dilution during the tests.
The key is to utilize; top grade oil, top tier fuel/fuel additives and change it regularly. Another is to do the preverbal
"Italian Tune Up," on a regular basis. I'm not advocating excessive speed just hard accelerations up to speed limits or whatever you decided to do. The worst thing for the 2.0T Theta engine II or 1.6T Gamma II is to drive it in short stop and go traffic regularly.
I've seen many older GDI's on the street regularly still running in good nick and they've been used on the road for more than 20 years now. You don't see a rash of civil laws suits against manufacturers utilizing them either. So, it's not a problem.
Due to fuel being injected within the cylinder, fuel type has a minuscule effect on carbon deposits, particularly on the back of the intake valves.
A true heated (via coolant) air/oil separator that returns oil to the system would be best, followed by a water/alcohol injection system, then dual catch cans (since they require routine maintenance)
This might work for the average owner on their dime but manufacturers will never utilize such a configuration, as it far too costly and maintenance intensive.
We've already seen members here, install CC (catch cans) and they've remove them almost as rapidly. Why, because it does little to catch such fuel/oil vapor and catches near nothing in the cans.
Multi-port fuel injection engine solves this problem and stays with in emission standards. Hyundai has a new multi-port fuel injection engine in a 1.6T configuration. They will be extending this engine configuration to all power plants in the near future.
The Multi-port engine is being released first in Korea.