Gaskets
Lets take a look a look at gaskets and some fundamentals.
Head Gaskets
Here is a well used CB23/60 head gasket:
So what are the fundamental parts of the head gasket...
The gasket starts out as a core plate with perforations that key in the softer surface facing laminates that are rolled onto it.
The surface facing is made up of fibres, fillers and binders that impart strength and conformal shaping to the mating surfaces. A common material used is graphite along with silicone.
The bore bridge is sometimes reinforced to overcome the extreme temperatures and loads found between the cylinders.You're likely to want some bridge reinforcement with turbocharged engines.
The borebinders or blast rings are obviously designed to take the full force of the combustion process. For standard applications stainless steel eyelets (ferrules) offer the best protection from fatigue and creep. Of course for extra protection you can have the block cut to accept steel O rings.
To inhibit the gasket acting like a wick and seeping coolant or oil, the bead acts to add internal compression of the surface facing. It does not prevent surface leakage.
So what are some rules of thumb when dealing with head gaskets, you ask:-
The gasket will typically crush to about 80% of it's shelf thickness once torqued down. This does not apply to copper gaskets, which don't crush much at all. There are also performance gaskets where the installed thickness is greater than 80%;
A head and block surfaces should be true to about 0.05mm (0.002") and surface finish maxed out at 2.5 microns;
Head and block surface hardness should not be less than 65 Bhn (Brinell). If you are replacing a gasket consider if your aluminium alloy head has exceeded 200°C, because if it has then some annealing would have occured and that 65 Bhn might be a difficult ask.
The borebinder ferrules should not overhang the bore chamfer.
Single torque head gaskets are applied without any sealant or lubrication because they have a sealant imbedded in the surface facing that does the job for you. They have a low relaxation rate and therefore don't shrink much at all with engine heat.
If you use a sealant on the gasket you must retorque the bolts after the engine has been run up to temperature. This is done by allowing the engine to cool completely and torquing to specs.
You must use a lubricant on the bolt threads, washers and bolt head mating surface. You can use oil or thread conditioner, in fact anti sieze thread conditioners are good when using steel bolts in aluminium alloy applications.
The bead usually mates to the cylinder head, not the block face. However there is always exceptions to the rule. Glycol is a slippery little sucker will run where water won't so if in doubt get a gasket with a bead.
Other Gasket Stuff
We are talking gaskets here, so when we say don't oil a rubber gasket we are not talking O rings or seal contact patches on shafts.
When you install gaskets you should make sure you use a wax degreaser or similar to ensure the surfaces are clean and oil free. If you are tempted to use a silicone sealer think twice, ask for expert advice, etc, because silicone on rubber will make the rubber or cork splay out and extrude, buggering up the whole process. Of course you shouldn't be using standard silicone sealant anyway because it cures hard and can ruin your oxygen sensor if it starts to act on the oil.
If the book says use some sealer get hold of an oxygen sensor safe tube and make sure you use it sparingly. Brands like Hylomar are considered amongst the best.