Use OEM transmission fluid...or all fluids really.
In this video, This Old House general contractor Tom Silva shares tips for keeping a roof free of moss and mold
When parking on a hill, apply emergency brake before shifting to park. This puts the force that prevents the car from rolling down the hill on the brake and not the transmission.
Recent Optima batteries are made in Mexico, not U.S., and quality dropped (while price increased). Avoid Optima batteries.
Ethanol is common additive, but should not be more than 10% or can damage the engine. You can buy a device to measure ethanol content.
Check your car model for recalls.