What lubricant for injector and insert O rings?

[SJ]

Previous posts:
Car Stuck! Engine Coolant boiling over
Need info on cylinder head removal

I'm putting everything back together again.

I made a rube goldberg injector tester which showed that no two injectors
worked the same . .and I tested 10 injectors. I bought new injectors.

The manual says to lubricate the O rings before putting the injectors in.
What kind of lubricant? Gasoline?
I was thinking of using silicone grease . . . like the type used for brake
calipers . . or dielectric grease.

SJ
85 Dodge PU, D-250, 318, auto
85 Audi 4k - - sold but still on the road
88 Audi 5kq
90 Audi 100q