I used to sell petroleum products years ago, so I know all about them. All lubricants wear out over time, no matter what. Synthetics are better at keeping viscosity near normal range for a longer period of time, and the shear factor is better, but the additives in lubricants break down as well.

Of course if one is off-roading with dirt, dust, and silt, then of course it will need to be replaced sooner than normal. There is no such thing as an automatic transmission is "sealed for life", which is simply not true, but that is what owners manuals claim now. The vent releases the hot vapors to atmo, and sucks it back in when the transmission cools down. That doesn't sound "sealed" to me.

As for idling, sure if it's super-cold out then warming the oil up makes sense. But in light vehicles using synthetics, I don't see warming the oil up for more than a minute at normal outside temperatures, unless one is not going to go easy on the gas, and instead immediately hit high speeds.

 

you are totally lost. Nevermind.