I am not big on the silicon gasket sealer. I like to use #2 permatex sealer. It's a black sealer that doesn't harden.
For oil pans and valve covers I like to use weather strip adhesive on the gasket for the oil pan or the valve covers and then very little #2 on the other side.
The weather strip adhesive does two things. It keeps the gasket in place while you close it up and for the valve cover it making it easier to clean and replace later. The gasket is stuck to the valve cover not the head.
I do the same thing on the timing cover gasket as well.
Typically, the purpose of any gasket is to prevent leakage, and (most) are designed to be used without any "sealant" at all.
"Gasket sealant" is an extra measure used to ensure no leakage. As a rule of thumb, when I want (or it requires) extra sealant, I always will use the sealant ONLY on the part that can be removed from the block . . .
i.e. On your oil pan, I would seal the gasket to the pan, and not apply any sealant to the block. That way, if there's a leak, or whenever I need to remove the oil pan, the gasket isn't sealed to the block which makes removal of the pan and any subsequent gasket work a lot easier because the gasket is sealed to the removable part, and not the block. (Ever try scraping off an old oil pan gasket off the underside of the block while it's still in the car??)
*raises hand* , I HAVE scraped gasket material off the underside of my block while its in the car. PO obviously put alot of sealer on the block itself.. when i removed the oil pan , the gasket basically was 100% glued to the block itself... to me, the worst part of my melling hv install was the gasket removal from the block, not only was it super time consuming and slow going but, i got SO MUCH debris and gunk all over myself in the process.. NEVER AGAIN, i hope.
Now just how many times do you have to scrape gaskets off an engine if you do it right the first time? I listened to guys like you when I built my GTO, and it ended up leaking. I listened to you guys when I built my GMC, and it leaked. I sealed it up tight with permatex #2 on my Mustang, and guess what? No leaks. So build your engine right, and seal it up tight. You'll thank me for it.
Sorry, but I take offense in that. We offer up our advice to help others. You don't have to take our advice, but you don't have to slam us for giving it either. I've never had a pan gasket leak in all the engines I've built in 27 years of working on cars ... because I've done them ALL right the first time.
I hate leaking pans, so I put a little non-hardening Permatex on both surfaces, and on both sides of the gasket. For cork gaskets that might slip, 3M weatherstrip adhesive will tack them in place. Lacquer thinner dissolves Permatex quickly for cleanup. Nobody reuses pan gaskets do they, so why not guarantee a seal on the b%$#%&&?
Valve covers are a good place to just glue the gasket to the cover so it can be pulled off and put back on (for those with noisy rockers - John?), although I've never succeeded in getting a long term leak-proof seal on covers without a touch of silicone. Such a stupid design, cork gaskets w/o a drip path.