Replaced the T-stat today, and diluted my 50/50 mix.
After diluting the mix by ~1/3 (one gallon purified water), and replacing the t-stat, the 10 miles highway run was about 190F in the afternoon heat. Best part was, instead of the temp climbing after exiting the highway and stopping for the light, the temp dropped. Made to run up at 80 and back at 85, and the temp gauge never hit the hash mark between 175F and max.
Not sure if the problem was in the mix or the t-stat, but seems to be good now. Might also have been an air pocket in the water jacket that didn't get burped originally. The old t-stat was dated 1/95, so it very well could have been in there for 6+ years.
While checking for leaks, I also checked the visco fan. At appox 2500 RPM (by ear) the fan disengaged. For those who don't know what to listen for, listen for quiet (sure beats trying to grab the bugger). You'll know what I mean, as soon as you hear the fan disengage. As the engine speed dropped, I could clearly hear the fan re-engage.
I will be watching fopr the next few days to see how well it handles the heat of the day (we're in a desert like heat wave right now).
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.