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#505078 - 02/02/04 12:56 AM warming up transmission fluid
shrek01GT Offline


Registered: 03/05/03
Posts: 66
Loc: Alberta, Canada
Just wondering if anyone can tell me if there is any advantage to warming up an automatic transmission in Neutral as opposed to Park? We just had a cold spell of -40C weather and I was just corious....

Thanks!

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#505079 - 02/02/04 01:28 AM Re: warming up transmission fluid
MolaKule Offline


Registered: 06/05/02
Posts: 14773
Loc: Iowegia
Shrek,

Check out this thread.

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=16;t=000743

My preference is to stay between 2k and 3k rpm until temp guage goes to at least 1/3 normal temp.

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#505080 - 02/02/04 03:38 AM Re: warming up transmission fluid
Anonymous
Unregistered


Does tranny fluid heat up in neutral? [Confused]

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#505081 - 02/02/04 04:36 AM Re: warming up transmission fluid
shrek01GT Offline


Registered: 03/05/03
Posts: 66
Loc: Alberta, Canada
I guess I should also ask if the fluid is doing the same thing in park as it is in neutral. One would think that if it wasn't being pumped in park it wouldn't warm up as fast as if it was flowing and in friction with moving parts in neutral....

I really have no idea what goes on in an automatic transmission incase you can't tell!

Thanks everyone!

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#505082 - 02/02/04 04:40 AM Re: warming up transmission fluid
MolaKule Offline


Registered: 06/05/02
Posts: 14773
Loc: Iowegia
Once the coolant heats up the ATF will eventually warm up.

Putting a load on the tranny will cause it to heat up faster. The load is having the selector in drive or reverse.

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#505083 - 02/02/04 04:47 AM Re: warming up transmission fluid
therion Offline


Registered: 01/18/04
Posts: 404
Loc: Palatine, IL
quote:
Originally posted by ZmOz:
Does tranny fluid heat up in neutral? [Confused]

Yes i believe it does becuase it cycles as soon as the engine is started.

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#505084 - 02/02/04 06:00 AM Re: warming up transmission fluid
Kestas Offline



Registered: 06/04/02
Posts: 10886
Loc: The Motor City
Park - Neutral...no difference for the fluid. They're the same thing except for the parking pawl engagement.

You're better off warming the fluid by driving the car.

[ February 02, 2004, 10:02 PM: Message edited by: Kestas ]

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#505085 - 02/02/04 06:40 AM Re: warming up transmission fluid
Anonymous
Unregistered


quote:
Originally posted by Kestas:
Park - Neutral...no difference for the fluid. They're the same thing except for the parking pawl engagement.

You're better off warming the fluid by driving the car.

Why do most (if not all) manuals/dipsticks tell you to check ATF in neutral? If it's the same for the tranny I would think park would be safer while the engine is running...

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#505086 - 02/02/04 05:58 PM Re: warming up transmission fluid
Kestas Offline



Registered: 06/04/02
Posts: 10886
Loc: The Motor City
I never noticed. I thought the manuals said to check it in park. That's the way I've done it.

Can you see a difference in fluid level when you check in park vs neutral?

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#505087 - 02/03/04 04:15 AM Re: warming up transmission fluid
Spector Offline


Registered: 06/10/02
Posts: 3224
Loc: Chattanooga, TN
All of mine say park. I would bet most manufacturers would never get that manual past the risk managers if they said to check it in neutral, too many accident possibilities.

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#505088 - 02/03/04 05:05 AM Re: warming up transmission fluid
Anonymous
Unregistered


quote:
Originally posted by Spector:
All of mine say park. I would bet most manufacturers would never get that manual past the risk managers if they said to check it in neutral, too many accident possibilities.

Says right on my dipstick to check in neutral. Also says the same thing in the manual and my Haynes manual.

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#505089 - 02/03/04 06:07 PM Re: warming up transmission fluid
RichR Offline


Registered: 02/21/03
Posts: 574
Loc: Chicago
quote:
Originally posted by ZmOz:
Says right on my dipstick to check in neutral. Also says the same thing in the manual and my Haynes manual. [/QB][/QUOTE]
You must own a Dodge/Crysler.

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#505090 - 02/03/04 07:29 PM Re: warming up transmission fluid
heyjay Offline


Registered: 01/14/04
Posts: 526
Loc: Manitoba Canada
As far as checking the ATF level, the fluid must be at operating temp: at least 20km / 12mi of driving.

For my 2000 GMC Sierra, with the motor idling and the truck on a LEVEL surface, slowly go through the range from Park to One and back to Park, letting it sit for about 5 secs in each range.

Then take out the stick and wipe it, put it back in, pull out and check the level.

This is per the Helm shop manual.

As far as cold weather use, the Brookfield viscosity has a limit of 100 Poise before shift solenoids/springs and the torque converter will fail.

Most conventional Dexron III ATF's reach 100 Poise at around -35 C.

If you operate HD Allison automatics, they REQUIRE a "preheat" in temps colder than -25 C / -13 F. The "preheat" means to use an electric pan heater or to run the motor in P (If equipped) or N for a minimum of 20 minutes.

They warn if you attempt range operation, as in driving off, you could cause transmission failure that would NOT be covered by warranty.

I've seen folks who have attempted to yank the selector into D at -40 and nothing happens. So they floor the pedal, somehow thinking that "helps." They grenade the torque convertor or main pump. I'd let it run 5 min minimum.

So I think it's important to use the correct ATF. If your car takes Dexron III, then in most parts of Canada and the Northern U.S. and Alaska, the regular Dexron III can not be used below -35 C.

FWIW Mobil 1 ATF, which is approved for Dexron III and Allison C4 spec, has a rated Brookfield of 51.5 Poise at -40. This is what I use in my automatics and very good operation, even at -42.

Jerry

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#505091 - 02/11/04 07:44 AM Re: warming up transmission fluid
Ed Offline


Registered: 08/15/02
Posts: 135
Loc: Southern California
Actually there is a difference between park and neutral (other than the pawl engagement)
The fluid is pumped through more passageways in neutral. The hydraulic diagrams definitely show this. I don't know enough about automatic transmissions to make a definite comment on why they are set up that way but it makes sense that because of this, the fluid level as read on the dipstick is not the same in Park as Neutral
Ed

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#505092 - 02/17/04 11:08 AM Re: warming up transmission fluid
Tony M. Offline


Registered: 03/10/03
Posts: 7
Loc: CA
I think in neutral, there is usually more fluid flow inside toyota the valve body,(the old 80' dodge, chrysler vehicle show big different) so it may show little lower fluid level. , but you should check after driving for awhile, take it ez to warm it up. feel the stick is little warm up to little hot(fluid end ), then park it on a level lot. take a reading. If there is no trans problem I dont worry about the fluid shows a little low or over, Not too much over(less than 10mm is ok). I got a big cooler(12in x 12in x 1/2in) in front of my truck, and the fluid level is still at full cold mark after 30 miles driving on free way in a cold day. In a hot summer day, it blowed over hot mark with a boat behind . I use the right type of fluid on the trans dipstick. Type T4 is handling heat and lube better than any other in T type. 'O' ring and clutch material in T4 fluid trans and Dex III fluid trans are all different in handling of that trans. I dont like mix ATF fluid, I use the same brand name, I like Penzoil Dex III. Mixing those fluid(type T and Dex II or III) may burn your clutch in long run. not right away. drain and refill 3 or 4 times at every other 10 miles trip will take care of mixing problems. Just want to share my thought, my $0.02 . sorry, I dont mean to hijack your topic.

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