Replaced water pump @ 180k. Did full Gooch flush and fill with 4 gallons Rotella ELC.

Burped and drove 50 miles at both on and off highway speeds. Checked level and tested freeze point with specific gravity type tester. Came up with -45 degrees.

Heater works great at idle and under normal driving conditions, upper hose gets hot and pressurized, overflow to degas working - so I assume pump circulation is good.

Is there some reason for the excessively low freeze point reported? Should be -34 at the 50/50 mix I have.

Is my Prestone coolant tester off? Should I use a different type tester for this application?

 

I always try all three of My testers for comparison,The Gooch flush got Me closer to -34 or 50/50,I use quality testers but never invested in the Refractometer which is supposed to be the most accurate

 

Got to thinkin' (sometimes dangerous).

While with CDOT I had to test the specific gravity of each delivery of mag chloride deicer. The test was specified to be done with the sample at room temperature.

The temperature of the coolant mix noted above was 25F - perhaps this would account for the discrepancy?

 

I hope it never gets cold enough in CO to find the real freeze point!

 

I have seen -40F. Fortunately, I had a garage to park in where it only got down to 0F.

Forty years ago I drove delivery on the west slope. Overnight stop was a motel in Craig where I plugged the Cat 3406 in and left the rig running all night. She was barely loping along come morning. Always carried extra fuel filters - no fuel heater on that truck.

I understand Elbert can get a might chilly.