Why do I need to push the mineral oil with a syringe from bottom to top when bleeding Shimano road brakes? Every tutorial on the internet, including Shimano official manual, tells me to do it that way, but nobody explains why.
Why can I not fill the funnel with new oil and let the old oil drain out the bottom? That's how I did it with my MTB brakes and it worked fine. Why the need to faff with the syringe for road brakes?