[CZroe]

Originally Posted by choneofakind

No, not the same thing.

Oil thickness controls damping. This controls how quickly the forks move.

Preload controls how much weight the forks require before they start compressing. This is how you set ride height. Note that preload does not affect the actual spring rate, it just adjusts how far the forks compress under static load. This is why the solution for having the wrong spring rate is getting new springs, not adding preload.

5W oil will give a nice plush ride because it creates little damping. However, this will come at the expense of a little front end feel. Also, it's more likely to experiencing pogo-ing with light fork oil because this reduced damping.

Oil thickness depends on the preference of the rider. Finding the right damping is about finding the compromise between feel and comfort, especially because both the rebound and compression damping are controlled by the same fork oil. We don't have fancy forks that can adjust those separately.

Well, good thing because last week I took apart those forks I rebuilt with 5W and will be getting 10w. FWIW, they say that the stock stuff specified in the service manual translates to about 7.5w.