great advice ! i the compression in the cylinders (1-6) is: 90/95/110/100/100/100. one odd thing is that when i checked the compression last week i was getting 135 in #5 now i get 100. the tail pipe is sooty but not oily. looks like it is running rich in the pipe. the water in the radiator does look brown. i just thought it was rust. could this be a sign of something ?