I put a 30w in. I think that's quite a bit thicker than standard, but it didn't make as much of a difference as I hoped it would. Not sure how much went in, used some rubber tubing and a funnel, just poured it into the funnel and pumped it until all the air was out. Less than 50ml I would say, but you have to buy it in half litre or one litre bottles, so there is loads of surplus which is just a waste now. Worth doing if you have some fork oil lying around, but probably not worth shelling out £10-£15 for a new bottle. Just don't put engine oil in. I tried that first, again as I had loads lying around, and it made it worse than was before!
Pitchfork how did you get the old oil out/new oil in, was it via that little torx bolt on the body of the damper?
Yeah, unscrewed it, pumped the old stuff out then pumped it again to draw the new stuff in. Couldn't be arsed to disassemble the end and do it that way.