I have a slight variation on this recipe.
1 cup oil
3/4 cup sugar or 1/2 cup Splenda/other sugar substitute (for diabetic folk)
1/3 cup ketchup
1/2 tsp salt (I don't use salt, this ingredient is optional. Honestly, you'll probably find it too salty if you add it unless it's more a pinch than a 1/2 tsp. You've been warned.)
1 tsp Worcestershire Sauce
1/2 cup vinegar
Mix all ingredients together using a small hand blender. Or whip it yourself with a whisk until smooth. For best results, make night before and let sit in fridge. This stuff can keep for a long time but it tends to go pretty fast in my house.
For those of you who need vegan friendly worcestershire sauce, there's a good recipe here.