gaskets o rings etc... for dummies

[82SC]

well as a budding DIY I have enjoyed doing engine work on my car...but I have some questions for the seasoned experts

while doing jobs on my car I've seen green and red gaskets and even some grey gaskets. Also I've seen green and red and black o-rings...

what do these colors mean?

I assume most gaskets have to be applied dry?
is it bad if you get oil on them?

do gaskets ever require sealant, or oil to make them work properly?
from past threads sealant seems to be more of a nuicense then good.

are gaskets side specific? like for the cam gasket there is a written side (paper) and a rubbery side...does it matter which side goes toward which? for example since it is keeping oil in the cam tower the paper side goes away from the oil side?

what about o-rings? sometimes you use silicone grease...is white lithium grease ok or only silicone based? do you ever install o-rings dry with nothing?

thanks...just wanted to clear up some rookie questions

MJ

[Zendalar]

Black is synthetic rubber (can't take gasoline or oils very well)
Black o-rings tend to harden when they age, and these are usually seen in carburators, even though they can't handle the gasoline very well. These are the cheapest o-rings.

Red is real rubber.

blue is silicone (good for high temperature, not soluble in gasoline or oils, can handle friction very well without breaking -> When pressure is released it should get back its original form).
Blue o-rings, are used to seal case halves in combination with those "case-through-bolts" (sorry, dont remember the word). When for example Porsche engine is taken apart these are usually to be found still very flexible.

I use sealing glue with paper gaskets, this is lacquer like material which binds the paper gasket between the materials. I have been using gasket-lacquer in carburator gaskets with very good results (with pure paper gaskets it leaked, no matter how thick the paper)...the name of the lacquer was ...Green something... =)

EDIT the EDIT: Yes, usually I oil all o-rings disregarding what material they are made of.