Can't believe all this talk about not leaving the car in a gear (preferably 1st gear or reverse) when parking because of stress and strain.
Like others, I've been doing it for over 40 years and never had a problem. I don't even
know of anyone who has ever returned from a transmission problem to say, "Yeah, the mechanic told me I'd have to replace "fill-in-the'blank" because I've been leaving the car in gear when I parked".
For all the people using strain and pressure (etc.) in their comments, are you just repeating what you've heard or could you be a bit more specific? For instance, is it wearing out something? Is it bending something? Is it making the metal more brittle? What...?
And, after reading through the post/thread, I notice no one mentioned (or else my scanning was too quick) using the front wheels as a third tool when parking on an incline where there is a curb available. Turn the wheels toward the curb when facing downhill and the other way when facing uphill. Put it in gear AND put on the parking brake. [edit] LOL and just noticed the last post before mine mentions using the wheels against a curb.
Having said all that, I don't have any idea if parking on an incline with an automatic tranny (in Park) is a problem or not. Haven't owned an AT since 1976.