Wayne:
You can come down from the ceiling -- her engine is most likely
not sludged. What you're looking at through the oil filler in a 1MZ-FE V-6, the engine in that vehicle, is an oil "baffle" that is coated with a black rubbery substance that I've been told by Toyota people is their to absorb valve train noise (hmmmm, not sure about that, but that's not pertinent). For whatever insane reason the coating is a thin black foamy/spongy substance that resembles a coating of sludge, but it isn't sludge.
I know what you're thinking right now -- "yeah right, he's nuts..." I'm not. But please don't take my word for it if you're at all inclined to doubt me. I offer two recommendations in support of what I've said. First, the photo below is of the filler on my then-nearly-new 2003 V-6 Camry. I assure you it looked this way on the day I drove it off the dealership lot.

[Photo taken in August, 2003]
Second, if this isn't enough (and that's OK if it isn't), please go to the nearest Toyota dealer and look for a new LE or XLE V-6 Camry. These two models, not the SE, have exactly the same engine as your RX. Inspect the oil filler on one, and you will find the exact same thing.
Oh yeah, here's a third observation. About three months after the above photo was taken, I saw the engine with that valve cover off for a seal replacement. The entire top of the front cyl bank head was totally spotless and without any sign of dirt, varnish, or sludge.
Happy Motoring!
[ August 08, 2004, 11:16 PM: Message edited by: ekpolk ]