Mercury 150 XR6 head o rings question

[Ron357]

The o rings have a flat side not sure if the flat side goes to the block or to the head side. the manual doesn't say.
Also is there any gasket sealer go on the heads at all?

[Merc 2.5]

I've never had a oring motor to work on but have tore few apart , and seems that flat side goes to block and round side in the head , don't know bout sealant, if orings, etc new should go on dry on clean surface.
Mite could use tad bit grease ( I mean tad bit) to hold orings n place

[Eastwoodnorris]

I just installed some a couple weeks ago and didn't know either. I put the flat side facing the block. The compression, leakdown and the "don't pee yourself I'm gonna send it" tests on the water all have been good.