Whereas the altenative to Gadaffi is likely to be better, with increased relations with the West, do any of us know what the likely replacement government of Syria would be?
You can't just cry 'Oil!' and think that's the argument won. Western forces are stretched, the UN refuse to get involved in anything until someone else takes the first decision, what is going to happen after must be considered, and alternatives decided upon considering that it's not our fight. It's not a computer game, you can't just reload if you get it wrong & reduce global stability further for whatever reason.
All the tin foil hat wearers would do well to realise that decisions are not taken in isolation, whole regions can and will be affected by regime change.