Grandma's Salad Dressing

From: AllRecipes

This dressing recipe has been in our family for 4
   generations. We keep passing it on since its so good, and pass it
   on to our guests who want it as well. Prep Time: approx.
   10 Minutes. Ready in: approx. 10 Minutes. Makes 3 1/2
   cups (28 servings).

1 cup vegetable oil
3/4 cup white wine vinegar
1 cup white sugar
1/2 cup ketchup

1/2 teaspoon salt
2 teaspoons Worcestershire sauce
1 onion, chopped

Directions
1 Prepare dressing in a large jar with a tight fitting
   lid. Add the oil, vinegar, sugar, ketchup, salt,
   Worcestershire sauce and onion. Shake until the sugar is dissolved.
   Refrigerate and shake well before using.