And the RAVE says that there are 45 rows in that radiator, so that would be horizontal rows of tubes, arranged in two cores. And our Dexcool sludge might be filling a number of the lower rows, even after moderate flush. They would be quite cooler than top rows. Heres a GM shop practice for flushing Dexcool, takes several hours....

Also, when considering slight overheat, don't ignore heater core, which helps pass water when stat is closed, and if that is slow, stat takes longer to open. As well as plugged metering holes in stat. Good thing about heater core is that two hose clamps and a short piece of pipe and you can bypass it for testing.

Yep, fan should not keep turning once you release, for more than 1 turn. Feels like peanut butter in there, not penetrating oil..