I have wondered about this too.  the roller under the door rolls on the
metal track.  There shouldn't really be slipping/sliding friction between
those 2 pieces.  I agree that greasing that roller and track would seem to
attract and hold grit and dirt which would then be ground up by the roller
or used by the roller to grind the metal surfaces.

I have seen people at the beach kick their foot against the sill of the
slider to get sand off before getting in the van.  This deposits a lot of
sand right in that track.  I have made it a habit and tell my camping
buddies to kick the sand or dirt off on the front tire instead.

Edward

On Tue, Jun 7, 2011 at 5:37 AM, Frank Condelli <RAlanen@aol.com> wrote:

>        Grease where you put it is just attracting dust & dirt that will
> eventually get into the BALL BEARINGS of the rollers.  It's the ball
> bearings that really need the lube.  Yes, it requires taking everything
> apart to get in there but just putting grease between the roller and the
> metal track it rides on is not the best solution.
>
>
> On 2011-06-06, at 4:37 PM, Automatic digest processor wrote:
>
> > I just cleaned / lubed all the sliding door guides a few weeks ago.  I
> used
> > "White Lithium Grease" which is a good choice for this purpose.
>