My 06 had a laeaky fork seal. Took it to my local dealer to have done while getting new tires. Had them replace the springs with RaceTech springs while doing it, and use the next heaviest oil as well. The result was worth it.
I have a 2008 M109R, 3rd owner. Seriously doubt fork oil has ever been changed. Has anyone done this without the special tools shown in the service manual? Any suggestions for doing it yourself?
The fork oil isn't on the maintenance chart. Some have replaces it. I just replaced my fork seals last summer. And if I was going to go through the trouble of removing them and changing the oil, I would atleast change the seals out. And if you were thinking of upgrading the springs, I would do that at the same time.
But, if you are just wanting to change the oil you can do it without any special tool. Just premeasure the oil, and poor it in. Just bleed it buy moving the rod with the cap still on up and down till you get all the air out.
You may find that you can spin the cap right off the rod anyways. Several noticed the cap was able to come off with just hand pressure.
I replaced my fork seals and also replaced with heavier oil. Went with the Amsoil fork oil. WAY better than before. I don't know how you could drain all the oil out and refill it to the proper level without taking it apart.
I've been riding motorcycles for 56 years and have changed the fork oil in one of my bikes because I wanted to, not because I thought I needed to.
That is an approach that I wouldn't take. I have been riding motorcycles for 5 decades as well. I have changed fork oil on all of the used bikes I have picked up over the years. Oftentimes going to a heavier weight. I can tell you that the stuff coming out has at least some noticeable degradation by way of gray sludge/suspended particulate. I have also had instances where the oil volume in the fork tubes was insufficient or not evenly matched.