Mix dry ingredients together and set aside in a very large metal mixing bowl. Or two smaller ones. Enough to hold the 18 cups of oatmeal. Then mix the wet ingredients together and pour over the oatmeal. Mix lightly with your hands.
Bake at 250 for 1 hour. Stir every 15 minutes until done.
Store in airtight bags or containers.
Madagascar Vanilla (purchase at Chefs Catalog) Of all the vanilla's I've used this is my favorite. Once you've tried it you won't go back!
This is the large type of bowl I use. Works great and is oven safe.