For those of us with the 8v-92 I have attached a sheet from my Owners Manual. It lists normal operating temperature ranges for gauges on the dash panel layout. I recall there being a discussion about this some time ago. It did not reach a conclusion other than someone needs to check with Detroit Diesel and Allison Transmissions. Well this attachment has answered all my questions. I think I'm going in for radiator service this winter as my engine temps have been rising above the mid point of the range.