I think this is a very importanttopic and needs further deliberations! The problem of re-refining/ useageof UEO is more acute in underdeveloped countried and it adds to more environmental pollutent load than any other thing! Be it by meance of adulterantto good lubricants, whereby dammaging the engine and resulting to air pollution, or by emance of draining to soil and drains without its proper collection whereby polluting the ground water !
But along with that what is more of important is themethod used for its re-refining! If an age old Acid -clay method is used, then we are basically doing more harm to the enviornment than doing any good! The other advanced methods are definitly environment friendly and leads to much better quality of the finished products, but arecapital intensive too!!! Moreoever, without a roburst Used Oil collection mechanism in place under the overall monitoring of the federal environmental agencies , countries like India, is having real problems looming at large! Only good thing to happen is banning of Imports of UEO to India!