Bf 109 Radiator/oil cooler on E-3/4

[LcSummers]

Hi guys, i dont know if something like that was posted but i ll try it. I was thinking a bit and want some feedback or help, please.

I read (dont know anymore where) that with the introduction of the Bf 109E-7 the flap for the nose/oil cooler vanished. All other models (F-K) didnt have them too.

My question is if let the cooler flap (not the cooling system under each wing) open all the time wich negative results or disadvantages do i have.

Why should i close it besides warming up engine?
Left it open all the time causes no engine failure!

Every comment is appreciated.

Thanks