Mix together packets of dressing and gravy, then coat roast on all sides. Place in crock pot, and add 1/2 to 3/4 cup water. I will also usually add some fresh minced garlic cloves (3 or so) and one small onion that I've chopped up at this time. Turn crock pot to low temperature. About four hours later, I add potatoes and carrots. I'll also eyeball the roast at this time, and will sometimes add another packet of onion gravy or au jus gravy and another 1/2 cup of water. Let roast and vegetables cook another 3 1/2 to 4 hours, until potatoes are tender and roast is 150-160 degrees. Remove vegetables and roast from crock pot, pour juice in crock pot into sauce pan. I make a thickening agent of cornstarch and water to add to the juice. Bring to a boil until it thickens, stirring constantly.