2002 - 150 Head gasket (O-Ring) Question

[pamlicopanther]

I am about to install a new set of cylinder head O-ring gaskets on a 2002 Mercury 150. After removing the head I noticed it appears something was applied where the head surface meets the block surface when it was initially installed.

I have the o-rings, but I am wondering if I need to apply something to these surfaces before installing the head.

Thanks.