Quote Originally Posted by BlackW1dow View Post
going back to the temperature scalars, how do yall know that the low MpH is based on 0MpH and the high is anything greater than 0MpH?
Just experience or is there something that says it?

Also what is too hot relative to coolant and oil temp? oil temp stays about 219°F / 104°C.
My experience is with $EE '(94 & '95).
'vettes make use of a separate scalar: 'Fan Vehicle Speed Boundary' in TunerPro, or 'Fan Hi/Lo Vehicle Speed Threshold in TunerCAT.
The vehicle speed boundary / threshold is 0MpH, so anything OVER 0MpH uses the higher speed fan-on settings.
Although GM did not bother to use this feature with F- & B-cars, they can also use this feature by specifying different 'High' fan-on settings.

To answer your 2nd question:
examine oil & coolant temps while cruising on the highway, then use the fan-on settings to maintain similar temps in stop'n'go traffic.
If the coolant is clean & the radiator heatercore & cooling fans all work properly, I see no reason why the coolant should get hotter than
221°F / 105°C.
I prefer lower temps - I typically turn on the primary fan @ 203°F / 95°C & the 2ndary (meaning both) @ 212°F / 100°C (coolant temps).