Does putting automatic car in neutral for long idling periods relieve any engine/transmission stress?

[Shel_B]

I think almost every automatic has this now but I've never seen nor heard these systems be liked nor appreciated very much. It's usually been my experience that it's mainly a gimmick and you get better results with putting the tranny in the appropriate mode (sport, tow/haul, etc).

Well, I'd suggest you talk with some people who have and use such systems. I personally know several people that fall into that category, myself included. I use it around town to prevent the xmission from hunting for the right gear in traffic situations, I use it when driving in the mountains in order to keep the car in the gear I want while going up hills and through twisties, and it's helpful to grab a lower gear instead of having to kick-down the transmission, such as on a long, gentle uphill drive. What has your experience been?

 

[Skippy722]

Well, I'd suggest you talk with some people who have and use such systems. I personally know several people that fall into that category, myself included. I use it around town to prevent the xmission from hunting for the right gear in traffic situations, I use it when driving in the mountains in order to keep the car in the gear I want while going up hills and through twisties, and it's helpful to grab a lower gear instead of having to kick-down the transmission, such as on a long, gentle uphill drive. What has your experience been?

Yep. Ram and Dodge has a “range select” that limits the transmission to whatever gear you selected. It will shift up to that point but no higher, it also disables MDS on v8 models. Very helpful to get pretty fine tuned engine braking on big hills thanks to the 8 speeds wide gear spread. My 300 had the paddles so I could put it in a gear (within reason naturally) and it would hold it till redline if I wanted it too, or downshift and up shift as I saw fit.

 

[PimTac]

Most modern automatic transmissions do this on their own without any input from the driver. The computer runs the show.

If it’s a long stop then either put it in park or shut the engine off.

 

[daman]

While in gear and stopped the TC is baking the trans fluid and using more fuel as the engine power is converted directly to heat within it. The amount of money you'll save in fuel alone over the long term would help pay for a new trans if you ever need one. and the cooler temps of the fluid may also help the trans live longer. Heat in the trans is the enemy ...not the wear on a shift linkage. How many of you have had your car completely jacked over up by an ASE mechanic? i rest my case.

^^^ 100% THIS!!!

been doing the N thing for 20+ years, leaving it in D just creates heat(you can see temps rising) and uses more fuel.

 

[Supersonic]

Used to drive cars that would stall out if not put neutral. Probably a trade off, takes the stress off the drive train and allows engine to spin freely which can also effect battery charging from the alternator is what I was taught and remember most. Saves on the brakes too, though that may also be from anticipating a stop and slowing down. I also prefer not to be at a stop where you are having to push extra pressure on the brake pedal. I do it all the time.

I don't drive new cars and not sure how it is for them, my newest being a 2012 and seems to be agreeable with the neutral selection, I can only hope the linkage last too, I can't recall an automatic to wear out because of shifting to neutral, whereas I have had manual linkage issues like plastic washer/grommets and three speed column shifts get caught between gears and had to be manually corrected. I do vaguely remember a Ford Escort having a linkage issue, I don't think it was related to shfting to neutral.

 

[clinebarger]

I wouldn't recommend anyone shift into neutral unless you're sitting for a extended amount of time like at a rail crossing....Then you might as well shift to park & relax.

Frictions & Shifter parts can wear, Chrysler A727 based overdrives are notorious for wearing the Detent Ball Bore making it difficult to shift from Park.
GM TH350 & 4L60E are known for Forward Clutch wear.....Though this is more from getting on the pedal before the Forward clutch is fully latched or putting it in drive while the vehicle is still moving backward.

If the transmission cooling system can't handle idling in gear.....The cooling system has issues or isn't adequate. A LOT of units have a Thermostat Bypass in the cooler circuit these days....If the temp creeps fast then levels off, That's why.

It's nothing for modern ATF to run 200-220 degrees, Surprised nobody posted that 40 year old ATF temp chart that TCI & B&M use to push cooler sales.

 

[ZeeOSix]

I only do it when I have to sit more than a minute at traffic lights.

 

[CharlesInCharge]

I was at a traffic light today, but it was out of order. The 4 way light was murder. Traffic backed up 1 mile in all directions. A true mess. Put the cr in park many times and it took 10-15 min. to go .25 miles thru a intersection. This is the reason I'm asking. This happens from time to time. Put in park.

 

[Crash Bandicoot]

I’ve never done this, and have had a few cars that have gone 200+k miles and have yet to need a trans rebuild or new trans. Feel like if you are changing your trans fluid regularly and doing normal driving, and this is the difference between the trans living or dying over the expected life of the vehicle than the engineers, accountants, and lawyers somehow ended up talking to each other.

Don’t auto hold systems these days leave it in drive and just actuate the parking brake?

 

[vavavroom]

I checked today if there was a difference in RPMs between idling in D vs idling in N/P. I'd say the difference is imperceptible on the analog gauge. I will also check with the digital readout.

What I'd like to know is why the design of the forward clutch allows wear in N/P. The clutch is a steel band lined with friction material that acts on a drum, I believe. It seems like even in N or P there isn't total separation but only slippage between the drum and the friction material. That's why the clutch wears in N/P. Why isn't the clutch designed to completely disengage?

 

[Leo99]

I think this is one of those solutions in search of a problem. My dad had to put his Rambler into neutral when stopped or it would stall out. That was a long time ago.

 

[joekingcorvette]

I would rather just keep the transmission serviced. I don't know of any game wardens or policemen that put their cars in neutral and they seem to last a long time. These public servants to a lot of surveillance and sit in one spot for several minutes. Every seen a highway patrolman sitting there waiting to pick up a speeder? Vehicles usually rust out before the trans goes if they have been serviced properly.

 

[Graham Piccinini]

Can't believe no one posted this yet. This guy explains it way better than I could. In short: NO, do not put your car in neutral at a stop light.

 

[RDY4WAR]

Jeez, why not just turn the engine off if you're stopped that long? Oh wait! Most "modern" cars ALREADY do that. Whoda thunk?

I drove a vehicle that has this feature for the first time yesterday. I don't like it. Fortunately there's a button to turn it off.

I'll coast in neutral if there's a long stretch of coasting and momentum can carry the whole way. Fuel economy seems better that way. I only occasionally do it if sitting for a long period of time.

 

[Graham Piccinini]

I drove a vehicle that has this feature for the first time yesterday. I don't like it. Fortunately there's a button to turn it off.

I'll coast in neutral if there's a long stretch of coasting and momentum can carry the whole way. Fuel economy seems better that way. I only occasionally do it if sitting for a long period of time.

Did you actually measure the fuel economy? Because when you coast in neutral - ECU is pushing fuel through the injectors to keep the engine running at idle speed. But when you coast in gear (manual or auto tranny) - the ECU completely cuts fuel until you press the gas pedal again, or until the RPM drops down to idle speed.

 

[atikovi]

But when you coast in gear (manual or auto tranny) - the ECU completely cuts fuel until you press the gas pedal again, or until the RPM drops down to idle speed.

Huh? If the ECU completely cuts fuel the engine would shut off.

 

[Graham Piccinini]

Huh? If the ECU completely cuts fuel the engine would shut off.

Nope.

 

[atikovi]

So how does the engine run without fuel?

 

[Skippy722]

So how does and engine run without fuel?

It’s not “off” since the ECU is still in full control, the engine just isn’t producing any torque. The torque converter is locked, thus the engine is still spinning. Below a certain speed/RPM or hitting the gas makes the injectors instantly start firing again. I can watch it happen on my Ram and Grand Caravan with my Bluetooth OBD scanner. Start coasting, there’s a pretty brief period before the injectors go to “0”, and they stay there till some parameter is met and they all come back alive.

 

[atikovi]

OK, I just know in the few instances where I've had the engine cut off while coasting, the car slows down pretty quick from the compression braking.