yean no, you wont have to change the engine. Theres no real worse case in this, just that you run it out of oil, then you'll be up for an engine change for sure. In my case, (not that I have heaps of money) but i'd take it somewhere to get done cause it is not (as above) an easy job and once you start, you have to finish it so maybe make a few calls, and see what the best price you can get (not always the cheapest is best!) and look at your cards then. As for auto, find your leak source. it may just be a pan gasket and that you can do in about half hour!