I have had a VW 1.6 td fall into my hands. they said it had set for years. I cleaned out the lines then ran some lucas stabilizer through and it cranks up and runs. It was sorta rough and the return line was nasty. The more I have ran through the engine, it actually does not sound bad and the return line is pretty much diesel instead of gummy junk it was. Would this be worth keeping or just scrapping?