TF998 Fluid Question.
#3027184
03/24/22 07:00 PM
03/24/22 07:00 PM
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Joined: Feb 2003
Posts: 4,798 Castlegar, BC, Canada
That AMC Guy
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Castlegar, BC, Canada
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Just about to fire up my '88 RAM for the first time. The engine was yanked in 2016, and I've spent the last few months putting it back together. Transmission was drained when the engine was removed.
Can't find and have been told Dexron III is obsolete. I was pointed to this Mobil brand stuff called D/M and on the back, it claims to be the modern equivalent of Dexron/Mercon III and is compatible with vehicles designed for that blend.
Anybody else run it? Good to go? Thoughts?
Bloody Mary, Full of Vodka, Blessed art thou among cocktails....
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Re: TF998 Fluid Question.
[Re: That AMC Guy]
#3027237
03/24/22 09:42 PM
03/24/22 09:42 PM
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Joined: Jan 2003
Posts: 1,607 westerly, ri. usa
440lebaron
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,607
westerly, ri. usa
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atf4 supersedes most mopar atf's its available anywhere
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Re: TF998 Fluid Question.
[Re: Sniper]
#3027358
03/25/22 11:52 AM
03/25/22 11:52 AM
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Joined: Jan 2003
Posts: 25,858 Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,858
Rio Linda, CA
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If the trans has a lockup converter (likely) then ATF+4 is the correct fluid. For a non-lockup 3-speed, Type F is fine.
The INTERNET, the MISinformation superhighway
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Re: TF998 Fluid Question.
[Re: 360view]
#3027686
03/26/22 10:07 AM
03/26/22 10:07 AM
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Joined: Mar 2011
Posts: 3,083 Michigan
A727Tflite
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master
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Michigan
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If the shaft torque applied exceeds the clutch friction holding torque, which depends on the ATF friction coefficient, how quickly do the clutch frictional surfaces wear to the point that they must be replaced in a rebuild?
Can it happen in one or a few dragstrip passes, or one or a few maximum highway accelerations?
I ask because I once changed out ATF+3 to ATF+4 on a high mileage 46RH.
After the change out I did a few full throttle accelerations up a steep high hill. Everything seemed OK, but a few hundred miles later the TC clutches began slipping, and a few hundred miles after that the overdrive unit clutches began slipping.
I later read in an SAE technical paper co-authored by Lubrizol Company and Chrysler that ATF+4 has a lower clutch friction coefficient than ATF+3, although ATF+4 has other numerous advantages. Why did you change the fluid to start with?
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Re: TF998 Fluid Question.
[Re: A727Tflite]
#3027824
03/26/22 06:02 PM
03/26/22 06:02 PM
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Joined: Dec 2005
Posts: 11,608 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,608
Fulton County, PA
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ATF+3 has superseded to +4.
Late model trans, stock, lock up, daily driver, ATF+4.
Performance, race, non-lock up, something else. Type F probably, Or synthetic Type F. Or Dexron.
If the results don't match the theory, change the theory.
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Re: TF998 Fluid Question.
[Re: A727Tflite]
#3027828
03/26/22 06:19 PM
03/26/22 06:19 PM
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Joined: Jan 2006
Posts: 8,162 USA
360view
Moparts resident spammer
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Moparts resident spammer
Joined: Jan 2006
Posts: 8,162
USA
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If the shaft torque applied exceeds the clutch friction holding torque, which depends on the ATF friction coefficient, how quickly do the clutch frictional surfaces wear to the point that they must be replaced in a rebuild?
Can it happen in one or a few dragstrip passes, or one or a few maximum highway accelerations?
I ask because I once changed out ATF+3 to ATF+4 on a high mileage 46RH.
After the change out I did a few full throttle accelerations up a steep high hill. Everything seemed OK, but a few hundred miles later the TC clutches began slipping, and a few hundred miles after that the overdrive unit clutches began slipping.
I later read in an SAE technical paper co-authored by Lubrizol Company and Chrysler that ATF+4 has a lower clutch friction coefficient than ATF+3, although ATF+4 has other numerous advantages. Why did you change the fluid to start with? The old ATF+3 was at the 30,000 mile interval. Neither Torque Converter Clutch or Overdrive Clutch was slipping before the change, but every now and then the trans was “bump shifting” while the truck was coming to a stop. After the ATF+4 and a new filter went in, the bump sifting was not felt anymore.
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Re: TF998 Fluid Question.
[Re: 360view]
#3027837
03/26/22 06:50 PM
03/26/22 06:50 PM
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Joined: Mar 2011
Posts: 3,083 Michigan
A727Tflite
master
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master
Joined: Mar 2011
Posts: 3,083
Michigan
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If the shaft torque applied exceeds the clutch friction holding torque, which depends on the ATF friction coefficient, how quickly do the clutch frictional surfaces wear to the point that they must be replaced in a rebuild?
Can it happen in one or a few dragstrip passes, or one or a few maximum highway accelerations?
I ask because I once changed out ATF+3 to ATF+4 on a high mileage 46RH.
After the change out I did a few full throttle accelerations up a steep high hill. Everything seemed OK, but a few hundred miles later the TC clutches began slipping, and a few hundred miles after that the overdrive unit clutches began slipping.
I later read in an SAE technical paper co-authored by Lubrizol Company and Chrysler that ATF+4 has a lower clutch friction coefficient than ATF+3, although ATF+4 has other numerous advantages. Why did you change the fluid to start with? The old ATF+3 was at the 30,000 mile interval. Neither Torque Converter Clutch or Overdrive Clutch was slipping before the change, but every now and then the trans was “bump shifting” while the truck was coming to a stop. After the ATF+4 and a new filter went in, the bump sifting was not felt anymore. Did it set any codes? What makes you think the OD was slipping?
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Re: TF998 Fluid Question.
[Re: 360view]
#3028227
03/28/22 05:27 AM
03/28/22 05:27 AM
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Joined: Feb 2003
Posts: 4,798 Castlegar, BC, Canada
That AMC Guy
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OP
master
Joined: Feb 2003
Posts: 4,798
Castlegar, BC, Canada
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I was surprised to see my dipstick is stamped "Use Type 7176 or Dexron II " Yes, Dexron II. So, if this Mobil says it's the direct descendant of Dexron III / Mercon III.... I guess I'll give it a try.
Bloody Mary, Full of Vodka, Blessed art thou among cocktails....
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