Temperature Rise

[sexycar]

Hi ..

I have a 82 ke70 corolla with me.. lately the temperature is rising slowly when I drive fast around 120km/h on highways at nights without traffic jams.

I've taken out the thermostat, totally reserviced & unclogged my
radiator, added clutch fan silicon oil but when i checked last night
it seems that the oil is leaking out of my fan clutch so I might need
to replace my fan clutch but then do u all think that driving at 120km/h
in the night would require the fan still? I think the air from the front
is pretty much already at that speed with the night weather temperature..
The temperature goes up pretty fast if I switch on the aircon now...
can anything else be the culprit besides the fan clutch? I checked
for water leaks, clogged fins & engine oil level too... everything seems
fine.. just wanna make sure before i change the fan clutch cos I find
it rather weird even if the clutch is slipping bad at 120km/h but the
night weather & speed that i'm travelling is sufficient enough with that
vast amount of frontal airflow ... hmmmm.... comments?