Thank you for your replies
@ Bernard Vinet: yes I know that BMW bikes are using some oil even the last GS models. But other French R3 are not consuming any oil. Am I the only one ? I am not a "pilot" and I usually change gear @ 3 500 rpm. I ride rather "cool". Ok sometimes I am going to 6 500 rpm, once or twice a day ride.
@ Pica: 0,25 litres with 3 500 miles that means 0.08 litres / 1000 miles which is nice.
@ Anonmeng: The dealership is using and I use this one:
Moto 4 Road ELF - Synthetic based - 15W-50 -