my buddy has a '99 cavalier with the 2.2, anyways he changed his oil and drove it for a couple of days, and it started to knock, well he just left it alone and i went over to look at it, it stays runnin, with a semi loud knock and when it idles for awhile it smooths out, well i check the oil and the stick is covered with a sludge all they way to the top! and no oil! at all! i'm like WTF, i take some off with my finger and i can feel like pieces of metal, and the oil smells burnt! so i'm debating to take off the oil pan! any suggestions?