Okay, I've got a 1992 cabover Mack with a 1996 E7 engine in it. On starting and running up hill or on flat ground no smoke, even on cold morning. Going down hill light blue smoke on de-acceleration. When I get to the bottom and hit flat ground again put my foot in it and get a ton of blue smoke for a few seconds, then it clears out. Nobody seems to know what's causing it. The consensus is if it was the rings it would smoke all the time. Somebody else suggested maybe the valve guides. Anybody have any ideas?