DI means direct injection, not diesel though.
It is the same type of system used for diesel engines, but adapted for gasoline. The MultiAir valvetrain in the Stelvio's 2.0 particularly, being hydraulic, is more like that then any other system. MultiAir is essentially a diesel engine's valvetrain matched to a gasoline engine. It is not like other GDI or DI engines in that way, it is mostly unique. The 2.9 V6 uses a different, non-hydraulic valvetrain system.
Yes having the oil black at 3k in the 2.0 is normal, like it is in a diesel, the same forces are causing it.
The question in my head is does that mean you should wait 10,000 miles to change it?
Just because the oil being black is "normal", does that make it healthy for the engine?
When you consider diesel engines recommend oil changes at 5000, due to carbon issues, using the same technology.......IMO,
No, you should not wait 10,000 miles to change it, do it at 5000-7500 max because even if black oil is normal... It isn't healthy long term.
Alfa makes the recommendations it does to ensure the car won't have problems under warranty (like everyone else but Honda, maybe), not so you won't have problems at 200k. I want reliability at 200k if at all possible and my recommendations are based on that.
Dirty oil is the enemy of a reliable engine, black oil is dirty, when it gets dirty... Change it.
I should add, 4 years ago I would disagree with myself and say the black oil is fine and you should just change it at 10k, because of what I have been told by various engineers, and what is spread throughout the industry as common knowledge.
That was before I realized how much fine, sand-like carbon residue is in engines after 10k miles.... Now... No freaking way. People always say someone is wrong when they come with new information...... IMO believing a 10k oil change is OK in a small turbo charged direct injection engine is like thinking the world is flat. Which was something the majority of people thought once (some still do).
To put it another way, and maybe make it more understandable, think about how much oil your car burns between oil changes....(realize some burning oil is considered "normal")
Mine burns about 3/4s of a quart over 10k miles, normally. That is 3/4 of a quart turned into carbon residue, inside the engine. That's what happens when oil burns, highly resistant or not. The oil in your engine that disappears - unless you have a leak - it is burning, it doesn't evaporate into nothingness.
3/4 of a quart (or greater then 10% of the total oil capacity) of nasty soot circulating through the engine for thousands of miles, clogging up the filter, causing pressure variations, stressing the oil pump, clogging the internal filter which will cause the pump to fail.........but probably not till 60-80k.
If you are ok with that, (or if you are lucky and don't burn any oil between changes)..... Then, black oil is normal and totally fine. Just change it every 10k and don't stress.
If on the other hand you do burn that much or maybe more and while you realize that is "normal", you don't like the idea of all that crud in your engine for thousands of miles.... Then change it more often.
Either way don't stress or think there is a defect in the engine. No defects, it is normal, oil will be dirty at 3k miles. The experts who say keeping it in there for another 7k miles aren't saying that because they don't think it's dirty... They are saying it because they think being dirty doesn't matter.
Decide for yourself if it does or doesn't.