There is only a couple of reasons to downshift. One, to be in the proper gear for exiting the turn so you can get full acceleration out of the turn. Second would be to slow your decent from a very steep grade.

I have used the down shift for years and it's a hard habit to fight. In a 5AT there is no reason to downshift in normal driving. But it can be done if you want the proper gear at the right time coming out of a curve.

BTW, I also think it's your tranny locking up the back wheels when you downshift. The ABS tries to modulate the wheels, but it can't as they are connected to the transmission.

 

I also downshift when I feel that brakes aren't necessary. Such as, if I need to slow down 5-10 mph in a fairly long stretch, I won't use the brakes, just downshift and let the engine do it. I just gotta break the habit of doing it when coming to sudden stops.

 

Why would you downshift in this situation? Again, it isn't even advised to do that in a 6mt. Brake pads are meant to be used because they are the most effective, cheap and easy to replace. Do you even have a clue of what you possibly will have to pay if something gives due to your engine braking technique of driving? Don't listen to us if you don't want to, but don't complain to us if you end up with an insane bill.

 

Engine braking does not place any load on the engine or transmission. You are simply using the vacuum in the motor to slow the car down. Your foot is off the gas so the injectors stop firing, there is no combustion taking place so no load on the piston, rod and bearings. The engine is simply pumping air through it.

The transmission gears are spinning like they normally would, again with minimal load. The gears are under much greater stresses when the car is accellerating and torque is being applied by the engine.

I can't see how damage can be caused by engine braking.

 

Im not really sure why every one is hating on the OP here.. In 5AT, if hes driving in Sport/manual/Tip, and approaching a red lite, you want him switch it back to D so he can press the brakes and slow down? That is very stupid. There is nothing wrong with assisting your breaks with down shifts. Every one has been comparing his situation to 6MT, but you dont shift at the same times (up or down) in 5AT. Also, even when in manual mode, and you start to slow, it down shifts for you as your RPMs go down... so doing it by yourself is the same thing..

 

It is generally agreed it isn't a substantial amount of engine wear that will be induced, but why even chance it? The transmission might take a bit more, but I agree in that it isn't a large amount. But again, why risk it? He isn't 6mt where there is the argument/reasoning to stay in gear vs going to neutral to be able to pick up in case of an emergency.

Personally I don't even see why he would need to get totally off the pedal to slow down only 5mph, even in auto cars it doesn't seem you would have to completely remove your foot to slow down that small amount. Unless he was trying to slow down that much really quickly, in which case the brakes would be a better choice.