itsalleasy
USA
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Joined: 07/20/2007
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wa8yxm wrote:
A study done many years ago suggested that motors on automatics lasted longer than the exact same motor on a stick shift because of reduced vibration at red lights caused by leaving it in drive.
Probably funded by the mechanic that said no fluid circulates in neutral.
If an engine is so poorly balanced the trans is needed to dampen vibration at stops it's not going to have much of a life expectancy. I sure wouldn't want to be near it if it makes it to 5000 rpm.
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tommy wilson
southern ca, usa
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Joined: 10/18/2001
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i have noticed that idling in drive will cause the allison transmission temp to got up so i have started putting it in neutral for long traffic lights or other delays like traffic jams on the freeway. md3060 allison.
tommy wilson
1996 kountrystar dp
spartan mountainmaster chassis
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Deen
Vancouver, WA
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Joined: 12/07/2000
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The transmission is designed to be left in gear when stopped, that's why the converter is there. Putting it in and out of gear adds to the wear on the trans due to the wear that occurs each time it's put into gear. But your transmission repair man will like you!
Deen - Vancouver, WA
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Ivylog
Blairsville, Ga. USA
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A 6sp Allison will heat the oil when sitting in gear. Just watch your temp gauge and it does not when in neutral. It's the torque converter slipping that heats the oil. Agree not worth doing at stop lights except in S Florida where it takes 5 minutes for them to cycle.
04 Monaco Dynasty 42' quad slide
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firstimer
Washington state
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Joined: 04/10/2007
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I "think" I heard a radio commercial the other day about a new Ford where the transmission automatically shifts into neutral when stopped, and shifts back when you're ready to go. They said it was to save fuel. I only heard it once...or maybe it was a dream.
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wa8yxm
Wherever I happen to park
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Allison does make some mention of that in their manual.. YEs, it will heat up the trans.. normally the length of a red light won't bother it but traffic jams might
Nothin adds excitment like something that is none of your business
John is Near Kenwood TS-2000 housed in a 2005 Damon Intruder 377
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apr67
Tallahassee, Florida
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Joined: 02/14/2007
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In gear and stopped has to use more fuel. The fact that the RPM's (idle) increase shows that the transmission is putting a load on the engine.
Of couse in a modern engine you could suspect it was some computer hockus pockus, but its pretty evident on carb or mechanical diesels.
Don't take your organs to heaven. Heaven knows we need them here.
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kjames90755
Signal Hill, CA
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First off you need to determine if your "Long Stops" are longer than the max. idle time listed in the users' manual, then decide. I leave it it drive for most "normal" driving, and the only time I've put it running in neutral was once we were on a site and I set the parking brake and ran the levelers, then it was shut-off time. Same thing leaving...run, in neutral, while retracting leveling jacks it brings trans. temp. up, then by the time retract is done, trans. is ready for driving at most speeds. 
2008 Itasca Meridian 37H, All. 3000MH (6-auto), Freightliner XC Chass., Cummins 6.7L Turbo, (Sweet! Delivery 03/12/08). Tow: '07 Dodge Gr. Caravan, Me, Him; Sugarbear, Apr. Toy Poodle; Pepe, Blk Toy Poodle; Hero, fat Siam.-mix polydactyl cat/Alarm Clock.
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ShapeShifter
Buffalo, NY
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In the grand scheme of things, it seems to me that any fuel savings, wear, or heat would be pretty insignificant, and not worth the effort of remembering to keep pressing buttons to go in and out of neutral. It seems like it would increase the odds of forgetting you're not in gear when the light changes, or of accidentally pressing the wrong button (like reverse?)
I agree with a previous poster that I couldn't be bothered for routine traffic stops. If it looks like a long delay, like totally stopped traffic, I would put it in neutral and set the parking brake, and shut off the engine if looked like an extended delay.
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KOG
Winterville GA
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apr67, you're figuring fuel consumption backward. On a carbureted engine for example, the throttle plate is at the same position in gear or out of gear. With the transmission in gear the engine is running slower and actually pulling less mixture (fuel and air) through that same throttle opening. Thus lower fuel consumption in gear. With injected gas engines and diesels idle speed is governed so that any drag at idle would increased fuel consumption. But the amount of drag is so slight that it's irrelevant. Transmissions with lockup converters have "loose" converters which have just about no drag at idle, unlike the nonlockup converter you'd have had on carbureted engines way back when.
Bottom line remains the same: shifting an automatic into neutral at stops is a waste of effort which only accomplishes more wear on shift linkage and selector valve.
And when my sister comes in from Germany for vacation every summer and starts shifting the car into neutral at every stop it drives me nuts. Some idiot there has perpetuated this "shift into neutral" B.S.myth too.
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