My car runs fine on freeway but in stop n go traffic the temp. goes from 90c to 110c until the aux. fans switch on and bring it back down to 100c.
The process is repeated until I hit the highway and she's back to 90-95c.
I changed the cap,thermostate and coolant (50/50)mix and radiator is 1 year old.
My only suggestion from reading the forum is the viscous fan clutch.
A few tests have been done and the results were:

1-on start up in the morning I take it straight to 2000rpm and I can hear a loud howl for 20 secs then it goes away.

2-When turned off cold,the fan spins freely.

3-When turned off hot,fan spins freely(same as cold).

This leads me to believe that it's the VFC (no fluid).Am I right?
If so how much fluid shall I put in?