I'm new to sous-vide and I am trying to figure out how to do it without vacuum. I've seen how other people have done it with oil to displace the air in the bag. But is this the best liquid to use? This is for pork. I am concerned the oil might change the flavor of the meat and was wondering if there is any other liquid I can use.
If you look here, at the last paragraph of Yossarian's answer, he gives you a fairly easy way of removing the air from a plastic bag without a vacuum.
Put your food in the bag and then submerge the bag in water just to the zip. The pressure will expel all the air. Then zip the bag up as you pull the closed portion underwater. This gets results comparable with a home vacuum sealer, I think, with the added benefit that you can include liquids easily.
While I wouldn't consider myself an expert on this topic, I wouldn't fill the bag with anything you wouldn't want to marinate your meat in.