I was using Look Keo pedals with grey grip cleats, and experienced a squeak from the one pedal/cleat per rev. This was not completely consistent with every rev.
The squeak would get worst with heavy or off the saddle pedaling. During the multi-day trip I would oil the pedal/cleats contact surface slightly, and the squeak would go away for awhile, but eventually come back. When I got home I replaced the cleats with new ones, and that was the end of the squeaking.
Recently, I replaced the pedals and cleats with new ones (Look Keo/grey grip cleats) on another bike. The squeaking re-appeared, but not so frequent.
I haven't got a chance to apply a light film of oil yet, and see the result.
Has anyone experienced this problem? Any suggestions are appreciated.
YannisG

This is a common problem with Keo cleats. Try a little grease on the contact plate of the pedal as well as were the cleat attaches to the pedal in the front and rear.

Oh dear god, this reminds me of the good old days of the first Look cleats and then the PD-6401 pedals.

They would creak incessantly after the cleats had a few hundred miles on them. The creak comes from the contact point between the back edge of the cleat and the clamping part of the pedal.

There were two ways to fix this, you have discovered the first which is to use some kind of lubricant. Pledge also works pretty well.

The second thing to try is to lightly sand the slick back edge of the plastic cleat just enough to take the polished/shiny look away. If you look at the back of the cleat, you will see where the contact point is polished smooth by the pedal clamp. Just lightly sand it with 400 grit sandpaper.

Repeat as necessary, neither are permanent.

I switched to SPD-SL a year or so after they came out. Pedal creaks are a thing of the past.

Thanks everyone for yr prompt responses.
I know oil solves the problem temporarily. I'll grease to see if it has a lasting effect.
I'll check the smoothness of the rear cleat surface, and rough it up a bit.
YannisG

Chapstick