Hello, What is the difference beetween the both operations ??? The oil i'll put inside each stringer must be the same than the oil is already inside the fork?? I would change the fork oil, because the fork is very smooth. The motorbike is 10 years old and i think nobody change the oil. Thankyou for your answer. Felix
Changing fork oil means, you dismount the fork strings, remove the screw on top of it, turn them with the top side to the ground and pump the oil out. For that you need 316 cm³ for each side.
The other possibility is to dismount the fork strings and disassemble them complete, maybe for cleaning the inner parts. For that you need 372 cm³ in each string after having assembled them.
By the way, maybe you should better change also the fork springs. The original ones are very soft anyway. So the better choice is to use progressive springs, for example Wirth-springs.