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

[Langing]

Thanks Bitter, that's yet more good, useful information. It is helping me, so thanks!

Now comes my confession:

At the head of this thread, I claimed there was no instruction in the BGB that described 'lubrication' of that distributor O-ring. I WAS WRONG! I was going by the 'other' reference (one of TWO) to reattaching the distributor onto the cylinder head.

Today, when I went at it again, I discovered, in the IG (ignition) section of Volume 1, 'IIA INSTALLATION':

1. REMOVE RIGHT HAND ENGINE UNDER COVER
2. SET NO. 1 CYLINDER TO TDC/COMPRESSION
blah, blah
3. INSTALL IIA

(a) Install a new O-ring to the distributor housing.
(b) Apply a light coat of engine oil on the O-ring.
© Align the cutout portion of the coupling with the groove of the housing.
(d) Insert the IIA. aligning the center of the flange with that of the bolt hole on the cylinder head.
(e) Lightly tighten the two bolts.

The procedure continues to add back the spark plug wires, the two IIA connectors, the negative terminal of the battery, then warm up the engine, connect a tach and timing light and set the timing of the engine before tightening down the two mounting bolts. (15 ft-lbf).

I apologize for unnecessarily bothering you helpful people. I have owned the (2) manuals for over 10 years, so you would think I should be able to read them by now, but I must have been rushing and failed to dig out the procedure to remove and replace the IIA. I knew about the (IG) ignition chapter being separate from the main engine details because I had been back there using the procedure to test the resistance of the primary, secondary and pick-up coils, because I wanted to know the unit was as sound as possible before reinstalling it after cleaning.

That being said, and considering Bitter's additional information, I notice that the O-ring that came with my engine rebuild kit (it fit the distributor housing) fits in a groove, and when installed is the largest OD of the distributor housing, so seals the hole it uses to penetrate the head. Before installing IIA, that O-ring does not take up all of the space inside the groove. Is that extra space in the groove used when the O-ring is squeezed to make the oil seal? I am asking because Bitter first recommended using silicone grease which is more like a filler (to me) and I had thought it might fill the gap I noticed in the O-ring groove. If the O-ring squeezes under pressure to fill the groove, then motor oil would make complete sense to me.