Fork Oil, 05 Reg, FZS !000

[Decoke Dave]

               As my bike will be kept permanently! Question is, should I change my fork oil?  The bike is soon to be 15 years old but only done just over 10,000 miles, as far as I know it has never been done ( I am obviously not the first owner).  If I should change it what viscosity of oil do you think is best , or do I stick to what Yamaha recommends?   

[kebab19]

There's a design fault inside the forks which causes rubbing metal surfaces to wear. The particles end up in the fork oil and get distributed all around the fork innards, causing even more wear.  Anyone who has changed the fork oil a couple of times or more will confirm: how much it stinks and how quickly it turns black.
That's a long-winded way of saying yes, change the fork oil asap 
5W is about right, 10W viscosity is too thick for the crude damping action.  I'm currently using 7.5W but my fork internals aren't standard 

[Decoke Dave]

   Well that's good enough for me!  Thanks. Someone on here changed the oil in their forks (FZS 600) after 75,000 miles, they thought it was a waste of time because the oil was so clean!  Obviously a different design.  Next job on the list.

[ogri48]

+1 what kebab19 says. And its well worth spending an inordinate amount of time cleaning the old shite out mate, not just pouring out the old and topping up with the new. You will be amazed how dirty and "pasty" your oil is...

[Decoke Dave]

Thanks again  .  So, as I have access to the required facilities at my paltry paying employment, IE an engineering workshop, would you say a total strip down, thorough clean of everything and rebuilt with new seals?

[PieEater]

Thanks again  .  So, as I have access to the required facilities at my paltry paying employment, IE an engineering workshop, would you say a total strip down, thorough clean of everything and rebuilt with new seals?

Definitely do the seals if they haven't been done, plastic and rubber degrade over time so even if the bike hasn't done may miles the fork seals will be well past their best. Replacement springs would be a worthwhile investment if you're doing a rebuild as the OEM ones are very much a compromise.

[Mustang]

Inspect the bushes and change them too