My 1985 300TD Mercedes-Benz's gas tank collapsed and the mechanic said that the evaporator lines were clogged. I filter my waste oil after it settled for a week through a 1 micron filter. I'm assuming that this is sufficient. He said that it could have been clogged from the previous owner using dirty diesel fuel. I'm the first to run it on waste vegetable oil. I don't want this to happen again so please let me know if it could be something I am doing. Many thanks.