Ride em til they break then get a new set. Works out cheaper than servicing the bloody things.
A litre of fork oil is about a tenner and does 33 odd services so the cost doesn’t seem too bad to me. ’tis damned annoying though.
There’s considerably more space in there than 15ml. You could get away with 40 easily – I used to in my nixons that have the same design.
Have you tried that on RockShox? I was using 20ml in my Revs for a while, but they kept blowing the wipers out. Pikes might do better as they have a proper oil seal, but Revs (and I think Rebas, Recons etc as well) don’t.
TBH, I’ve considered putting something like a 2.5mm thread tap through the casing between the upper and lower bushes, and a similar drain point at the bottom of each slider leg. I could seal them with an appropriate screw, and then draining out old semi bath oil, and putting in new would be a dead easy.
An oil port seems like a good idea, but If you want to simply replace the oil, you don’t even need to remove the lowers anyway … just undo the bolts, drain the oil, and squirt some new stuff in with a sryinge.