[Chris Doughty]

with big holes and thick oil Vs small holes and thin oil - you (within reason) get a similar 'slow' speed damping.

the differance is at high speed (piston speed, not car speed) (landing a massive jump) the thin oil flows faster through the small holes compared to the thick oil through the big holes and the thin oil flowing fast becomes turbulant and less efficient at getting through the holes, and 'packs' up a bit making the damping a little stiffer.