I have a 4 speed manual trans, but this is really applicable to any vehicle. I just shared my specific application I was thinking of.
I'm not talking about using an electric 110V heater. I'm talking about using engine coolant to heat the transmission. Thinner oil, lower viscosity, lower churning losses, especially in winter.
It would be pretty simple to make a heating block out of whatever and bolt it to the trans.
Here is an example:
