In a heavy 3.5 quart pot over medium heat, add oil, butter and chopped onion. Cook and stir onion until it has become translucent, then add chopped celery and carrot. Cook for about 2 minutes, stirring vegetables to coat well

Add ground beef, ground pork, a large pinch of salt and a few grindings of pepper. Crumble meat with a fork, stir well and cook until meat has lost its raw, red color

Add milk and let simmer gently, stirring frequently, until it has bubbled away completely, approximately 30 minutes

Add wine and let it simmer until it has evaporated, approximately 30 minutes

Add tomato sauce and stir thoroughly to coat all ingredients well. When the sauce begins to bubble, turn heat down so that the sauce cooks at a lazy simmer, with just an intermittent bubble breaking through the surface. Cook, uncovered, for 3 hours or more, stirring from time to time. While sauce is cooking, you are likely to find that it will begin to dry out and the fat will separate from the meat. To keep it from sticking, add ½ cup water as necessary. At the end of cooking, however, the water should be completely evaporated and the fat should separate from the sauce. Taste and season with salt