Almost ran out of gas today. made it to the station. put $20 of regular unleaded in (as usual). drove away, check engine light went on and white smoke started coming out of tailpipe with a very strong smell. indicated we used all of the gas in about 20 miles. engine making a strange sound clanging - oil is okay and so is trans fluid. oil does need changing though and was down 1/2 quart. never had this happen... Any suggestions?