ATF Fluids

MolaKule

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I posted this in another thread but this may be of interest to the whole board. I have made some minor additions to it. The main requirements of an ATF are thermal stability and friction modification (lubrication), with some anti-wear additive for the Sun, lock-up, and Planetary Gears, and of course, the needle/pin bearings. Add about 0.05% of anti-foamants (siloxanes) and some red dye for leak identification, and you have an special Hydraulic Oil called, 'ATF.' The formulator will tweak the additive package for each base oil type (group) or mixes of base oils. Here is the chemistry for an ATF such as Dexron III: (Average additive concentration by wt.% taken from seven (7) different additive packages) Phosphorous - 0.3% AW additive Zinc - 0.23% AW additive, anti-oxidant as ZDDP Nitrogen - 0.9% AW additive Boron - 0.16% Detergent and AW additive Calcium - 0.05% Detergent/Dispersant, tbn base chemistry Magnesium - 0.05% Detergent and base chemistry Sulfur - 0.55% FM and AW Barium - various% used as particlate control In the newer ATF oils of Group II-III, added esters of lineoleic esters, TMP polyol ester, and PE polyol ester, and other carboxylic esters, act as FM additives. The Additives phosphorous, sulfur, and boron are usually added in the form of esters when formulated with the base oil. For fully synthetic oils, the PAO and polyol ester bases are the main Friction Modifiers. The Mercon chemistries usually have higher concentrations of nitrogen and phosphorous. Boron and Phosphorous act as the main AW additives if the ZDDP is low or non-existent. Calcium and magnesium are, of course, base metals and provide the "basicity" to keep acids in check and provide the starting tbn. It has been found that ZDDP will turn the red-dyed ATF brown through oxidation, so some formulators have reduced or taken out the ZDDP and replaced it with other AW additives. [ February 18, 2003, 04:18 PM: Message edited by: Patman ]
 

Al

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The Boron (high), Calcium (low), and magnesium(low) seem out of wack. [I dont know] It would seem that all ATF's would have some fatty acids like tri-gliceried esters, or liquid wax esters that ATF's did not have in 10 years ago?? Can you shed any light here. My main concern is that lubeguard has these liquid wax esters. What are your thoughts. Especially on the Mobil 1 ATF which I am converting in the hopes it is better. I wonder if the Lubeguard is worth a darn with the Syntetic ATF.
 

MolaKule

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Al, The calcium and magnesium need not be as strong in ATF as in IC engines, because these dispersant/detergents don't have to work so hard removing (cleaning) the carbonaceous deposits and sludge created by blowby. The borates (as in boron) are multifunctional additive's that work as Anti-Wear additives, as detergents, as anticorrosives, and as anti-oxidants. The fluid not only acts as the lubricant, but also acts as the power (torque) transfer agent. In doing the latter, it gets hot and tends to oxidize the oil. The main requirement for calcium, magnesium, and to a lesser extent, boron, is to keep the internals clean of any oxidized particles so they can operate the hydraulic actuators and valves. Periodic fluid replacement with filter changes replenish the additive package and allow the mechanic to obeserve the amount of material wear in the transmission. With synthetic ATF fluids, I see no reason to use Lubeguard unless you are having a shudder problem or you need to extend the operation of a highly oxidized fluid until you can have the problem corrected. [ February 13, 2003, 04:38 PM: Message edited by: MolaKule ]
 
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So what is it in ATF that provides the 'super cleaning' when they add it as an engine flush? I'm not advocating anyone do this but given that some do (ie, the post under the atf section), what detergent or ester chemistry is producing these stories of great egine flush cleaning properties. I do not see detergents in any greater concentrations that regualr motor oil.
 

Al

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quote:
Originally posted by nick778: what detergent or ester chemistry is producing these stories of great egine flush cleaning properties. I do not see detergents in any greater concentrations that regualr motor oil.
I think you may have answered your own question. [Big Grin]
 

MolaKule

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Old wive's tales from long, long ago. Actually a few less detergents than engine oils. Compare this against Delo and the Delvac's.
 
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So, is it being stated that ATF does not have any better inherent cleaning ability than a good synthetic or delo type motor oil? I was under the impression that one of ATFs primary objectives is to keep a transmission very, very clean as the clearances are tight and the trans action is all hydraulic. Also, I'm a little confused as you don't see folks i.e., cleaning parts with motor oil but you do hear that they do with ATF. I understand why one shold not do a flush with ATF (sulfur, etc) but does ATF have inherently better cleaning ability than good motor oils? I presume the answer is no but would appreciate a confirmation. Thanks...
 
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nick778, to see for yourself, just visit a local junkyard and pull the transmission oil pan off a 30 year old car. The transmission parts are likely be amazingly clean (at least they have been on the 30 year old Asian cars I've inspected or owned) even if the transmission fluid is brown from oxidation.
 
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Some say yes, some say no it appears. Would still like to get some consensus based on fact and/or chemical make-up of ATF. If it indeed has better inherent cleaning abilities than good oil, it must be in the ester chemistry as it doesn't show up in the detergent make-up...
 
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Nick778, Transmission sumps don't see combustion by-products, including dilution by fuel - THAT'S why they are cleaner than engine oil pans. There is nothing chemically in ATF that would make it a better cleaner than engine oil. Most ATF's are 0w-20 or 5w-20 grades, so by thinning out the old oil it may drain more completely. This may be where this nonsense about using ATF as an engine flush got started. Ted
 

MolaKule

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I have to agree with Ted. It is not a matter of additive package, but of viscosity as to the source of this old wive's tale about ATF being a flush. ATF is 0W20 to 5W20 and thins out the engine oil. Take a thick 10W40 of 'yore,' and add some ATF and the result is a thinner oil that might act as a mild wash. The Auto tranny sees no combustion gasses, no silicons (unless the dipstick become unseated), so the tranny case is essentially sealed. The main requirements of an ATF are thermal stability and friction modification (lubrication), with some anti-wear additive for the Sun, lock-up, and Planetary Gears, and of course, the needle/pin bearings. Add about 0.01% of anti-foamants (siloxanes) and some red dye for leak identification, and you have an ATF. So, using an ATF in an engine is a waste of money and causes the engine's lubricating fluid film to reduce in thickness. [ February 18, 2003, 04:18 PM: Message edited by: Patman ]
 

MolaKule

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For automatic transmission fluids, the Level of Specification, whether it be a DexronIII(H), a Mercon variety, Toyota T-IV, Honda ATF-Z1, or whathaveyou, DOES NOT specifiy the base oils. The fluid developer must come up witha fluid that meets the specification for oxidation resistance, friction modification retention, etc. Ususally, an additive company like Afton (formerly Ethyl) or Lubrizol, or Infineum, or XYZ, comes up with an add pack for that specification. They then suggest a base oil mix for that formulation. The formulation gets tested, and if it passes, everything is hunky dory. Usually, it doesn't pass the first time and has to be tweaked for various reasons, such as for example, friction modification retention. After testing, the additive supplier is confident the additive package can meet the specification requirements for various base fluids. As the specification heat is turned up, higher Group fluids must be used, such as Group III minimum, in order to pass certain tests.
 

MolaKule

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Thanks Benjammin, I knew of at least one UOA and I had originally posted two DexronIII/Mercon fluids in the VOA section. Jimbo, Was the UOA of Mercon or Mercon V?
 
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quote:
Originally posted by MolaKule: ... Jimbo, Was the UOA of Mercon or Mercon V?
It was initial fill from the rebuilder. Ford specifies Mercon for this trans.
 

MolaKule

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quote:
This question comes up so frequently we'll answer it here as well. Q: It gets me to wondering... what exactly ARE these [ATF] specs? Do they cover additives, viscosities, or what? A: The specifications are "Perfromance" specifications in which the fluid is required to: resist shear and oxidation for a minimum period, and to provide and retain dynamic friction coefficient for a number of hours or miles. It must also resist corrosion and resist interaction with certain metals. The viscosity 'range' is also specified. The specification DOES NOT specifiy the type of oil or additives one must use. The formulator works with an additive company to develop a fluid to meet these specs.
 

MolaKule

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Updated Listing:
quote:
Here is the chemistry for an ATF such as Dexron III: (Average additive concentration by wt.% taken from seven (7) different additive packages) Phosphorous - 0.025% from AW additive Zinc - 0.0008% AW additive, anti-oxidant as ZDDP Nitrogen - 0.1% Dispersant and Friction Modifiers Boron - 0.016% Detergent and AW additive Calcium - 0.02% Detergent, tbn base chemistry, corrosion inhibitor. Magnesium - < 0.0005% Detergent and base chemistry Sulfur - < 0.55% AW AntiFoamant - 0.005%
 
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