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]

It does. . . by more than a half mm. OD (O-ring)-OD (shaft) > 0.5 mm. But the unused space visible in the groove is an appreciable fraction of the full O-ring thickness distance. If I knew how to post a picture, I would love to show you what I mean.

[Bitter]

It does. . . by more than a half mm. OD (O-ring)-OD (shaft) > 0.5 mm. But the unused space visible in the groove is an appreciable fraction of the full O-ring thickness distance. If I knew how to post a picture, I would love to show you what I mean.

I think I understand what you mean, the groove is wider than the O-ring, sometimes that's OK cause the rubber compresses and fills the groove. Usually the O-ring is more closely matched to the groove width...usually.