Time to replace a slow leaking gasket on the oil pan of my 1990 5.9L first gen Cummins. Given the unique was my engine has been installed (complicated supports and cross members) it'll be quite the process. Curious which might provide the best seal over the long term: custom rubber gasket for this year and make of engine or hand application of Permatex Ultra Black Maximum Oil Resistance RTV Silicone Gasket Maker?

I've used Permatex Ultra Black on my differentials and it works great. I'm also planning on pulling my transfer case and sealing it with Permatex when summer rolls around. But I keep hearing that oil pans are different and thus a custom rubber gasket might be best.

Any thoughts on what's best here?

Thanks,

Michael