Fork Oil for my upside down forks

Hi, doe anyone know what kind of fork oil is good for a GSXR 400, and does it actually make a difference what kind you get. e.g. racing, high density etc. I haven’t a clue. Also, how difficult is it to replace upside-down fork seals??

suspension is quite complicated. Its a lot to bite off if, as you say, you don’t have a clue. Don’t try to run before you can walk. Just stick to the standard oil, it will tell you in the workshop manual. You can buy it from Halfords. Get a mechanic to do the seals as you probably don’t have the propper tools at home. It shouldn’t cost more then half an hours labour, or if you’ve got the money you can just send them away for a full rebuild.