leon-b, you can use any oil to keep your knife rust free, but I suggest you use an edible oil like sunflower, vegetable or olive oil. Then you can use your knife for food prep!
I've had a good day out here in Germany, and I cooked sausages skewered on a stick, bacon hung over the fire, and a bean feast in my billy can. I went with my five year old daughter and a mate from work who said he would never have dreamed of cooking using the techniques that I used, he couldn't believe how simple they were!! He said he would have tried to make a whole big grill over the fire like a barbeque, which just goes to show that with a bit of thought and knowledge, you can save yourself a lot of work!
I hope you have fun on your outings, stick around here and you will learn all sorts of ways to do things, and you'll have fun doing most of them!!