why do some manufacturers engineer their oil pans to require a rubber gasket and others require RTV. my two examples are the honda B-series engines that have the rubber gaskets compared to the nissan sr20det engines that call for RTV.
is it cost savings or is one a better design than the other?
Give you a piece of information I get frequently from my gasket/seal vendors when I consult with their engineering on application specifics.
Whether its factually true or not I don't know but both manufacturers say basically the same but I don't do anything in automotive design to know personally.
Its a cost savings as a result of a design in many cases. ( not to mention that modern sealants are often superior in traditional sealing applications where high pressures or temperatures are present)
In applications where the gasket is also not moonlighting as a shim, there is a requirement for both a certain material rigidity as well as compression for a gasket to function properly.
I am told that in order to try to meet CAFE standards and cut costs overall that the traditional thicknesses and sizes of components are often reduced to where sometimes traditional gaskets would be prone to fail. That would either mean a different gasket configuration ( rubber, O ring, Groove or machined fit) or a different sealing technology like RTV products.
Personally I don't know but it sounds like exactly what I see clients doing in everything else for the sake of the bottom line.