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Fork oil -- real viscosity vs label

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I'm looking to replace oil in front forks on my S for first time. By reading http://www.pvdwiki.com/index.php?title=Suspension_Fluid I got dilemma about what viscosity oil to put in. From this page it seems that real viscosity of Motorex 5W fork oil is much higher than stock Showa 5W oil. In fact real viscosity of Motorex 2,5 seems to be about the same as Suzuki/Showa 5W, so if I want to get similar result as stock shock, should I actually use Motorex 2.5W, not 5W?

I don't mind the forks to be somewhat more stiffer as I also have 28l Aqualine tank, so Motorex 5W may be better choice but from that spec it seems that Motorex 5W is actually even thicker than Showa 15W!

Anyone changed to Motorex 5W from stock? How it feels?

Another questions - should I replace oil seals as well, even if they are not leaking (I have K7 with about 20K miles)? Manual says to replace with new and my mind also tells to do that but just want to save some $$ as the OEM seals are not cheap around here.

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Fact is, viscosity is not that critical on modern suspension valve designs. Use name brand fluid in the recommended advertised viscosity.

As for seal replacement, up to you. I would probably not replace seals that were not leaking. Depends on how much it would bother you if you had to go back and do the seals some time soon if they did not hold up.

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Thanks for your opinion. I'll give Motorex 5W a try when weather gets warmer.

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