Is oil below the top half of shocks indicative of failure, or is it supposed to be visible?
One repair tech said that any oil below the top half of a shock indicates failure. Another repair tech said that oil below the top half is normal because it gets distributed along the lower half every time you go over a bump.
Which repair tech is correct?
A shock absorber is supposed to be dry on the outside, leaking fluid (I suppose you mean that by grease?) is a sign of damage. The more hydraulic fluid a shock absorber looses the worse is it's capacity to dampen impulses.
I cannot indicate by what amount of leaking fluid a shock absorber is considered to be exhausted. Since the shock absorber is a highly important part of the suspension my personal strategy is it to replace them immediately if I see fluid leaking. When replacing them replace always both shocks on an axle.
