Tortise, I have had some experience with Redline oil in my 2000 300 EXC. After some time using this oil, my mileage dropped significantly. In races that I could complete with less than one tank of fuel, I found myself running out on the last lap. I also leaned the jetting, checked the float level, and completely rebuilt the carburetor. It got worse. I did some checking in the various forums and found that other people had the same problem with the only solution being replacing the caburetor. Three people with whom I compete who are "A" Hare Scrambles riders also said they had to replace their carburetors. One guy on a 200 EXC replaced his carburetor twice. The common denominator in all these cases was the use of Redline Oil. I bought a new carburetor, and changed to a different oil. Immediately, my old jetting worked again, and I was getting over 70 miles on a tank of fuel.
I cannot specifically indict the Redline Oil. I can only suggest anecdotally that the oil seems to have caused the problem. Do a search on Redline oil. You will see that others have had the same problem.