I recently installed a pyrometer with the probe inserted in the exhaust manifold. I didn't realize the temperature fluctuated so much. I think I saw somewhere that anything over 1350 degrees is high. I noticed that my truck is running between 700-800 on fairly level road and on inclines 5-6% grade up as high as 1100. On the grades I am driving in D with the o/d off. The truck is not loaded. I am concerned that when I have a load I will easily exceed the 1350. Anyone know if this is normal or do I have a problem? If I have a problem please offer suggestions. Thanks