Demonstrations began. Things escalated. A civil war broke out. Gaddafi and the government were being naughty (using aircraft and snipers to target demonstrators.). Rebels didn't like that. The choice that NATO had was either get involved to prevent more bloodshed or allow the fighting to continue.
There is no need to assign responsibility to "oil interests". Sometimes a cigar is just a cigar.
Yes the kind, humanitarian NATO. How many times has NATO intervened in such a military capacity in sub saharan african civil wars, of which there's been many? Did they give a crap about Rwanda? Did NATO intervene during the Second Congo War that led to 3 to 5 million civilian deaths in central Africa?
No, but the U.S. did send troops to try to bring stability to Ethiopia (not a big oil supplier there). And they were also involved in military action in Kosovo (again not a big oil producer).
Now, you could say that the U.S. has been inconsistent. But the actions by the U.S. in each case needs to be judged according to the geopolitical situation at the time. A change in the presidency or congress, the willingness of allies to participate, the relationship between the targeted government and the U.S., even media attention are all relevant. It not as simple as "Oil=war, No oil=no war".
I mean with Russia in general. Crimea is one example. Putin played Obama and Trump for fools. I can't think of a more cunning leader in international relations than Putin.
So, they kicked Russia out of the G8 and imposed sanctions.
Given the fact that Crimea was geographically located near Russia, and the U.S. had no real military presence in the area, I'm not really sure what Obama could have done differently. Send in military forces? That could end up in a shooting war with Russia.