I had a GTO with a 389 V8 that if you ran it in the mountains and then shut it off, it would climb past 'H'. And my /6 will do the same; not sure if it will go up to 230 since I just have a stock gauge. If the engine returns to normal temps after a restart and a few minutes of running, then it looks OK. You can always go back to the 180 t'stat, to see if the sludge is now gone or jsut changed it in summer.

Glad that the white stuff is gone. How does the oil feel temp-wise after running on a cold day now?

Oil feels good and not luke warm as it did before. Everything actually heats up now. Thanks again for all the help guys!