Originally Posted by Captleemo
With this Tacoma I started to shift the automatic transmission into neutral whenever I'm at a red light
as I believe it reduces wear and tear on the transmission.
Actually, it's the opposite.
When you're waiting at a red light
in gear, there is absolutely no wear on the transmission. The torque converter is slipping, and that causes no mechanical wear at all.
Wear occurs when gears are selected. When a gear engages, there is a slight wear on the clutch pack every time, just like when you let go the clutch on a manual. It only lasts a split second.Once the gear is engaged, there is no wear. When the engine is under load (ex: accelerating) this wear is more important. Of course it normally takes thousands or millions gears shifts to wear out a transmission, and when the engine is idling the wear is minimal, but still, shifting from D to N or N to D for no reason engages and releases the 1st gear clutch, and not only offers absolutely no benefit it actually causes unnecessary wear.
Regarding the torque converter slipping: in an automatic, the torque converter is what replaces the clutch found in manual transmissions, it links the engine with the transmission and the rest of the gear train. Imagine two ventilation fans facing each other. You turn one fan ON, the other will spin too (a bit slower) because of the airflow. Torque converter works the same, except the fans are a turbine and an impeller and they sit in the transmission fluid. The engine spins the turbine, which drives the impeller and the transmission, creating an hydraulic coupling between the engine and the drivetrain. This "soft" coupling allows the turbine and impeller (the engine and transmission) to spin at different speeds and makes smoother gear shifts. When you're stopped at a right light
in gear, the turbine spins but since you are not moving the impeller doesn't. There is no contact or direct link between the two, there is no wear, it's just the oil circulating around.
In a word: shifting in N at stop lights
is not a good idea.