Mark, you made an important point, we just compensate for nitro by changing the engines comprestion. So really it shouldn't matter which nitro content we use as long as the oil content is good. My first 2 v-6's lost comprestion way to soon so I decided to just use norvel fuel. When I used 15% omega fuel I couldn't lift the heli and I tryed every combination in the book all the way down to 1 washer. I have been watching the temps very closely and I get 198 f at the head and 220 f at the cylinder base with 25% norvel and 5 washers in this weather. The v-6 with 15% omega ran hotter and that was at a setting just enough to lift off the ground. Just my experience so far.. Alan