1. Drain all four cans of beans, discarding liquid.
2. In a large container, toss beans with onion and garlic.
3. In a 2 cup mixing bowl (or measuring cup), mix the oil, vinegar, Splenda, salt and pepper.
4. Pour over the bean mixture.
5. Mix well to coat all ingredients.
6. Cover, and let marinate in the refrigerator overnight.