Vintage West Bend Slow Cooker number settings verses hi low settings

You should consult the owner's manual for your slow cooker. According to one manual on West Bend's website:

There are five numbered heat settings on the heating base, 1 to 5. Heat setting # 1 should only be used to warm dinner rolls, muffins, etc. Heat setting # 2 should only be used to keep warm cooked foods for serving, whereas Heat Settings #3, #4 and #5 are to be used for actual cooking of foods. Set the dial directly at the numbered heat setting or midway between the numbered heat settings for complete temperature control. DO NOT USE A HEAT SETTING BELOW # 3 FOR ACTUAL COOKING OF RAW FOODS AS SLOW COOKER DOES NOT GET HOT ENOUGH TO COOK FOODS AT SETTING #1 OR #2. Set heat setting and cook food for recommended time as given in recipe. As a general guideline, most meat and vegetable combinations need 7 to 10 hours of cooking at Setting #3 (low), 4 to 6 hours of cooking at Setting #4 (medium) or 2 to 3 hours of cooking at Setting #5 (high).

Your particular model might have different instructions.

I cook on 3, mine is from late 70s and still going strong. When the meat and veggies are done, I turn it to 1 or 1.5 to keep warm.

I received mine as a wedding shower gift in 1980. It still works as good as the day I got it. I usually cook a roast for 6 hours on the #4 setting. It falls off the bone and very moist! Add 1 or 2 cans of Campbells Golden Mushroom soup and 3/4 package of dry Lipton onion soup mix over the top and it makes its own delicious gravy!