One time i took a load of scrap and remember seeing a huge pile of gas tanks that were removed from cars and then crushed in a very large pile of nothing but gas tanks, so i dont think it is a problem. but different places have different rules
there's a place in Clio that takes vehicles without even looking at them. I took an 89 F-250 back that had about 8 gallons of used motor oil that the previous owner left in the bed of the truck along with the propane tanks that the truck ran off (still had LP in them) - they could have cared less.
but like its stated above... different places have different rules.