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?