I often drive on a road that has lots of long stop lights (about a minute to two). A friend said she usually shifts into neutral when at a stop light, saying it’s better on the car. I think it’s better than putting it into park (since cars behind you may not see your brake lights if you put it into park & then step off the brake pedal) or shutting off the engine (which may put more wear & tear on the starter or battery). Does this save on wear & tear, save gas & produce less emissions too?? Thanks for any insights!
This actually increases wear and tear.
When you take the transmission out of gear, and then subsequently put it back into gear, the transmission’s clutches must disengage and then re-engage, all of which means more wear for your transmission. Just leave the transmission in the Drive position.
And, relative to VDC’s comment, I’ve seen far too many people slam the trans into drive as they push on the gas too soon and rpms are way up when the trans engages, BAM.
Your drive will be overall smoother the whole trip when you just leave it in drive.
That shifting back and forth also causes a delay in your moving when the traffic does, causing a delay wave throughout the line behind you.
In gear , if the traffic inches forward you can too ( by just letting off the brake ). If the traffic gradually accelerates, you do too.
Just an overall smoother more peacful trip that going through all that.
It also adds more stress to the rest of the drive-line.
I put the trans into neutral for long traffic lights of which there are more than just a few now. With the transmission in neutral, the engine idles faster which promotes better oiling of parts such as pistons that depend on oil supplied by oil vapor made from centrifugal splash leakage from connecting rod and main bearings.
When you put the transmission back in gear, do so with the engine idling and with the brakes off to minimize driveline shock.
This may be guesswork, voodoo and black magic but it makes me feel like I am doing more good than bad. Beyond that, transmissions are cheaper than engines. When someone with genuine test knowledge such as that from a motor vehicle driveline engineer or test technician provides experienced information, I will do what I think is best.
If anyone can say with authority that correctly maintained automatic transmissions fail more frequently than correctly maintained engines, then that might be a good point to go by.
I suggest you not worry about the transmission but place your automatic into neutral or even park at stop lights only when it becomes a safety factor. This might include, extended waiting periods, pedestrian crossing directly in front, stopping on a steep hill that requires more than slight brake pressure…etc. You be the judge as to when you would want a car in neutral, and not drive while waiting for you to pass.
I don’t think it takes an engineer to notice how few cars these days have engines that expire prematurely from lack of oiling at idle. If you drive a car with the VW 1.8L Turbo or the Toyota V6 that had sludging problems, I could maybe see it. But I think you’re just putting more wear than necessary on your transmission. But whatever works for you.
I’ll put the car in PARK if i’m waiting at a train intersection. Other than that I don’t mess with the trans. Seems like more trouble than it’s worth.
I think your friend thinks intuitively, that the engine is less stressed in neutral because it is allowed to idle freely. Someone should explain to her how a torque converter works. Check out http://auto.howstuffworks.com/auto-parts/towing/towing-capacity/information/torque-converter.htm