My 863 with 970 hours has high oil consumption. I'm guessing one gallon every 2-3 hours. The air filter was very black and soot covered. It smokes heavy black smoke during start up. The machine runs strong and has no other issues. My research suggests either a head gasket or a bad turbo. We will pull the turbo first and from what I've read any slop in the bearings would be indicative of failure. I have both a diesel compression test kit and a leak down test kit. Will either of those point out the head gasket.