I have the gas tank out of my 78 Monte and it is about 3/4 to 1/2 full of a oil gas mixture from sitting for 17 or so years. Its rotted on the inside and I decided to just get another one but not sure how to dispose of it? They frown on pouring oil and gas into the ground. and the tank being flammable do I just chuck it in a dumpster? Any help would be appreciated.