15

I drive a 2013 Mazda 3, in case that makes any difference to the answer.

There seems to be a few discussions on the web which indicate that putting an automatic car into neutral does not significantly improve fuel economy.

However, I developed this habit of putting the car into neutral at stop lights, and have been told by a few friends that this is bad for my car's transmission. This answer seems to agree with that assessment, but does not provide any convincing evidence that the wear on the transmission is significant.

Does putting my car into neutral at stop lights significantly damage the transmission?

In particular, assuming that I maintain all parts of my vehicle as recommended by the manufacturer, will this habit significantly increase the likelihood that my tramission will fail before other parts of my car do?

  • 1
    Does it not have a 'Park' position? Either way, leaving an auto in 'Neutral' while stopped will cause no harm. – Sam Apr 21 '16 at 9:48
  • 2
    @Sam, I think the argument for why it might cause harm is the frequent shifting to and from Neutral, not being in Neutral itself. – merlin2011 Apr 21 '16 at 9:49
  • 1
    I suppose it might have a very small impact on wear but not to the extent that it will "increase the likelihood that the transmission will fail before other parts of the car". I would however suggest that you just use the brake pedal, it defeats the point of buying an auto if you're always shifting! – Sam Apr 21 '16 at 9:56
  • 2
    I have to add that since you have this habit, it's going to take you much longer to move your car than anyone else if you have to do so quickly. I see it as a safety issue and a rather bad habit unless you're at a particularly long light. – JPhi1618 Apr 21 '16 at 13:01
  • 1
    Adding to what @JPhi1618 said about safety. If you get rear-ended at the light then your car will be sent rolling into the intersection; unless of course your car has safety features which engage the brakes when a crash is detected. If you simply have the clutch pressed down then your foot is likely to release the clutch and the natural resistance from the engine will help you to avoid rolling into an intersection. As for the wear-and-tear question, I fail to see how it causes any measurable harm to the transmission compared to leaving it in gear. – MonkeyZeus Apr 21 '16 at 14:40
12

No. Not by any significant or even measurable amount. Constantly using the shifter may, over time, wear the bushes and linkages prematurely but these parts are usually inexpensive and simple to replace. The transmission itself will be unaffected.

6

It could be argued that by putting the car in Park or Neutral, you are saving wear on the torque converter, which can be an expensive piece of equipment to replace. But I can't site any first-hand examples where that needed to be done, so again, the wear is likely negligible. :) I'd worry more about flushing your fluids and providing other regular maintenance more than whether you wear out your torque converter or your linkage, brushes and bearings.

6

It shouldn't as stated above, but there are bushings and bearings that will get worn out, its probably better to just leave it in gear.

Engineering Explained did a good review on this, so I recommend checking this out:

Engineering Explained Automatic Transmission

1

Breaking it down,

  1. Does sitting in Neutral put less wear on the transmission than Drive?
  2. Does the act of moving from D to N and then back to D put wear on the trans?
  3. And... (OP's overall question) do either of these "significantly" damage (i.e., cause to fail sooner than other parts) the transmission?

So...

  1. Perhaps surprisingly, putting it in N wears the clutches (and leaving it in D does not); see this answer.
  2. Obviously, moving the shifter causes stuff to move around -- linkages and mechanisms -- so of course there's wear on those moving parts.
  3. Is it enough to matter? That's the $100,000 question, and will depend on the particular transmission and car. I think it's safe to say the engineers know most people will leave it in D at stops. The owner's manual doesn't mention anything. On the other hand, it does say things like "Don't shift from D to R while moving!" so that's the sort of thing that will do the kind of "significant" damage you are asking about.
0

No. No. No.

It will not harm your transmission, actually, quite on the contrary.

When you stop and leave the tranny in Drive, both, the engine and transmission are trying to push the car forward (even if only slightly) and the brakes are keeping the car still.

If the transmission is in Drive mode while the engine is turning, you're actually forcing the tranny to slip internally (only one half of the torque converter spins and this heats up ATF) to accomodate to an engine turning while the tranny is in gear and the wheels are NOT moving.

Switch to Neutral as much as you can when the car is not moving, it'll save your tranny from unnecesary heat (friction) and wear. Heat is the number 1 enemy of automatic transmissions.

  • Seriously, if heat is the #1 enemy, shouldn't you be concerned about heat while driving, as the load put through the tranny is much higher than it's when the engine is just idling? Besides, the heat is not friction, it's hydraulically produced. Clutch operates through friction, torque converter operates through hydraulics. – juhist Sep 12 '18 at 17:13
-1

i think shifting gear from drive to neutral while on stop light would help to reduce friction in the transmission rather forcefully stoping the engine movement on drive by braking it. logically the manufacturer will not put neutral on automatic transmission if it is cause harm to the part, because the different select on the gear has its own function.. P R N D D1 D2..

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