Distributor O-ring lubricant? Options

[Langing]

1994 Celica ST, 1.8L, Manual

Rebuilding the engine after 300,000 miles and an overheat incident. Need information that isn't in the BGB.

Trying to reassemble the IIA (distributor) into/on a 'remanufactured' head. The part of the assembly that goes into the head goes through a largish circular hole, and there is a large O-ring (distributor O-ring?) riding in a square cross-section groove cut into the IIA that supposedly seals the hole so oil does not escape from the head.

Some places I have read that the O-ring should be 'lubricated', but there is nothing about that in the Repair Manual (the big Green books). I had an unpleasant experience when I rebuilt the disk brakes a couple of years ago. Because of the 'lubricant' I used on the slider pins, the rubber ring absorbed something from the grease and made it swell such that the pins stopped sliding. Am I about to do something stupid again if I 'lubricate' this O-ring? And, what 'lubricant' or grease should be used to make that O-ring create a proper seal?

TIA

[Box]

Let it soak in motor oil for a few hours before installing, can take a little bit of what your going to fill the engine with after rebuild and do it in a Ziploc bag or small plastic cup.