Useful info guys! I also wonder about the pit stop settings in the standard gui box (dont know about any UI difference there in new build?) where wheels, tyre pressures, front wing can be adjusted if I remember correctly - I cant find a way to adjust fueling amount in that box. Please help
Since refueling is not supposed by be activated in the first place with this car, everything regarding that is kinda buggy here. The refueling option in the garage is activated by mistake in the first place, that's why you see no option to refuel in the pit-menu on the track.
I for one will try to always start with the complete fuel-amount and not have to rely on the buggy refueling ever. Unless it turns out I would just screw myself this way strategywise, then I have to rething that unfortunatly. I hope not, since then we would have stuff like falsly refueling your car when having to do a repairstop and all that crap.
The amount of fuel you set in your pitstop will be refilled every time you make a pitstop, no matter if it's 1 or 3 or 7. That's why the defualt setup is set to "+0" because it is supposed to not refill you.
About radiators: Rad 3 or 4 for engine is working. Whatever keeps you under the overheating mark (yellow engine temps in trackmap-plugin indicate the start of overheating).
Interlagos with 29° air temp seems to barely work with rad3. 4 is safe everywhere under default temps.
Brakes: I usually use ~30% closed, depends on the track and how many hard braking zones it has.
Most proper drs-tracks should have the DRS only working in the drs-zone(s) during all sessions. I don't know if that is a setting in the track itself or where it exactly is.
In the case of Interlagos here it's free to use everywhere you want in q, but in the race it is open only in the one DRS zone which starts somewhere in the middle of the s/f straight.