FORD F-250 ENGINE BURNING OIL

I Have A 02 Ford F-250 With A 7.3 Diesel & Its Using Oil. But I Dont See Any Liks. What Could Be Causing It To Use The Oil? But It Still...

The Truck Fires Up Very Easily And Quickly And Runs Very Very Strong. When I Start It I Get A Big Puff Of Oil Smoke Then It Runs Somewhat...