Why aren't these types of gasket makers more popular than RTV silicone gasket makers? It seams like there is some risk with over use of RTV sealants such as on the BRS/FRS recall rebuilds and excess being sucked through the oil system and plugging it up.
What does the RTV have over an anaerobic sealant that will only cure in the absence of oxygen and stay liquid if it gets into the oil and doesn't cause any issues. I'm guessing the RTV can handle larger gaps and maybe more movement but for tight fitting surfaces the anaerobic sounds better to me.
So where should I use one over the other?
They are used all over the place. The problem is that the two components being sealed to each other need to be dowelled to each other and have near perfect machining. This is fine for engine block halves or multipiece cylinder heads, or even structural oil pans (that are dowelled) but not so good for components that are made of dissimilar materials, aren't dowelled together, or otherwise may see some sort of relative motion while in use.
It is amazing how much thermal expansion and stuff will make things shift around even if they are bolted firmly together. I think most head gasket science is making something that can stay sealed and also allow the head to move around on the block.
They are also not always the best idea. See the VW engines with a valve coverless 2 piece cylinder head that will start drooling oil onto the water pump, destroying its O rings. The anaerobic sealer doesn't hold. Whiteblock Volvos use the same head setup and the early ones were real bad for developing oil leaks. I assume they did a few sealant updates over the years since the newer ones don't drool all over the place like old 960s did.
