Thanks Ed and Steve,
Our C12 runs at 192 or lower most of the time, except if we are climbing a mountain range while flat towing then it may go up 200 or 205 on real hot days. But will cool right down with a idle break.
But I really do wish I had a better handle on the coolant level. So with your advise I will lower the Cap pressure and add a overflow tank.
And I will continue to check the surge tank in the same way as Ed, sticking the finger in.
Also, I will look into adding a bullseye level indicator, I will report back as to it's function and success with the surge tank.
Thanks again,