Cooling System

Can distilled white vineager be used to clean out the cooling system of a 2003 Tundra?

As an additive? No. As a flush, not likely. White vinegar is a mild acid that is useful for household cleaning but is unlikely to be of much value in clearing out deposits in your radiator. If you are looking for a green method of flushing your cooling system, be aware that the most toxic ingredient of a coolant change and flush is the used coolant. Use a brand name flush and collect all fluids and dispose of all of them properly. That’s the best you can do. Our town has a single day each year to dispose of accumulated household toxins for those of us who will never just sneak them into the trash. I keep my old oil and old radiator fluids etc. in the new fluid containers of the materials replacing the old fluids until I can dispose of them using this resource.
As an acid, white vinegar may cause damage to your cooling system. Use it to clean the bathroom and your floors.