Can Dexron VI be used as PSF?

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Hi, Can Dexron VI be used for a power steering system that calls for Dexron III? I tried searching but couldn't find anything. \:\( This is my first post, but I have been reading BITOG for awhile.
 
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I too, am wondering the same thing! What car do you have that calls for Dexron III ATF as the power steering fluid? The owner's manual for my 2001 Mitsubishi Eclipse specifies Dexron III as the factory fill.
 
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It's just now being validated as a PSF. iirc, Chrysler uses ATF+4 as PSF and is my prefered fluid for that purpose. It appears MB went back to ATF from Pentosin, probally ATF+4 too. BMW guys should definately still use Pentosin, for everyone's sake, lol. A lot of Audi guys bagged Pentosin a long time ago. It bites. If your system calls for Dex-III, I would definately switch over to Dex-6 w/o concern.
 
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I seem to recall when I was browsing a Pontiac G8 owners manual that it spec.'d Dex VI for the power steering fluid. You have to keep in mind when reading the above bottle that GM rarely has spec'd ATF for power steering fluids anyway so when they put the above wording on their Dex VI bottle it could be they just didn't bother to verify it would work or not since most of their vehicles wouldn't be affected. I'm curious if anyone is already using it for power steering fluid where a Dex III is spec'd. I don't know why it wouldn't work but I'm no expert.
 
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Dex VI is a lower viscosity than Dex III This is from a recent 2009 GM tech article
 Quote:
TIP: Any vehicle that previously used DEXRON-III for a manual transmission or transfer case should now use p/n 88861800 (88861801 in Canada) Manual Transmission and Transfer Case Fluid. And power steering systems should now use p/n 89020661 (89021183 in Canada) Power Steering Fluid.
 Quote:
TIP: Just because another auto maker does not require use of DEXRON-VI, this does not imply that their required fluid is in any way inferior to or better than DEXRON-VI. It simply means that the other auto maker has established its own, unique fluid requirements. Their transmissions may be built with different materials, and may be designed to perform in different ways, neither of which is necessarily inferior to or better than GM's transmissions, just different. Variables include the material used for friction surfaces, the material used for reaction surfaces, the types of control mechanisms and the characteristics of the factory fill fluid. This means that each manufacturer must tailor their transmission fluid requirements to meet the needs of their own transmissions. And a fluid may cause entirely different performance when installed into transmissions of different designs
 
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They won't recommend something until it has been validated. Since validation is expensive it is often just not worth the expense on existing product that works fine anyway.
 
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 Originally Posted By: Audi Junkie
It's just now being validated as a PSF. iirc, Chrysler uses ATF+4 as PSF and is my prefered fluid for that purpose. It appears MB went back to ATF from Pentosin, probally ATF+4 too. BMW guys should definately still use Pentosin, for everyone's sake, lol. A lot of Audi guys bagged Pentosin a long time ago. It bites. If your system calls for Dex-III, I would definately switch over to Dex-6 w/o concern.
What do some Audi drivers now prefer to Pentosin?
 

BimmerMan

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 Originally Posted By: silverrat
New Nissans and Infinitis use Dexron 6 for power steering.
Really? Interesting ...
 

BimmerMan

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Your right! This is from a 2009 Nissan Z owners manual... Power steering fluid (PSF) Genuine NISSAN PSF or equivalent*6 *6: Canada NISSAN Automatic Transmission Fluid or DEXRON VI type ATF may also be used.
 
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I used Dex-VI in a Scion TC power steering system. It worked great, but then the factory fluid left really disgusting deposits on the reservoir, so I don't know if this is a fair comparison.
 
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Originally Posted By: Mike_dup1
fyi from the bottle of Dexron VI
Here is the mentioned GM service bulletin. The main difference between Dexron-VI and Dexron-III is the fresh-oil viscosity, 6.4 and 7.5 cSt, respectively. However, Dexron-VI is synthetic or synthetic-blend and therefore uses less viscosity-index improvers, which means less shear. As a result, they both have the same lower limit on the viscosity after oil shear (for used oil), which is 5.5 cSt. The concern for manual transmissions and PS vane pumps would be the 15% lower fresh-oil viscosity, which may result in a little less wear protection. However, the difference is not that great and these systems work in boundary-lubrication regime (metal-to-metal contact) anyway, and in this regime the main wear protection is provided by the antiwear additives such as ZDDP and moly. It wouldn't be a great concern if you used Dexron-VI in a manual transmission or PS, especially a fully synthetic one such as Valvoline Dexron-VI. For peace of mind, you might want to use an appropriate manual-transmission fluid in a manual transmission. PS system is probably even less of a concern and if you really think you may need a tad bit higher viscosity, stick with Dexron-III then. In my opinion chances of increased wear due to this slightly lower viscosity is small -- after all, they wouldn't risk expensive automatic transmissions without being sure that the lower viscosity is providing the same protection. To me, the warning on manual transmission and power steering sounds like they just didn't want to bother to test and recommend the Dexron-VI on these systems and chose the easy way out of not recommending it instead of spending a lot of money to test it so that they can recommend it for those systems as well.
 
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Originally Posted By: Gokhan
To me, the warning on manual transmission and power steering sounds like they just didn't want to bother to test and recommend the Dexron-VI on these systems and chose the easy way out of not recommending it instead of spending a lot of money to test it so that they can recommend it for those systems as well.
Oddly enough, the G37 manual specifically calls for Dexron-VI for the power steering (or OEM PSF, of course). The fill cap just mentions Dexron ATF, but the manual actually mentions the Dexron-VI by name.
 
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Reactivating an old thread. The only function of the power-steering fluid is to serve as a hydraulic fluid. It doesn't lubricate parts under mechanical load. (Such parts are lubricated by moly grease.) The main difference between Dexron III and Dexron VI is the viscosity. Amsoil lists the viscosity at 100 C for their Dexron III and Dexron VI as 7.5 and 5.9 cSt, respectively. Power-steering fluid temperature rises to about 80 C during multiple large steering movements such as when parking. Therefore, the main difference between Dexron III and Dexron VI when used as a power-steering fluid will be the steering-effort assist. Since Dexron III has a larger viscosity, it will generate a higher pressure, which will result in more steering assist and less steering effort than with Dexron VI. The difference could be about 10 - 30% depending on the system and particular fluids used. Other than that, during system tests, the technician will see a different system pressure with the two fluids, which may be somewhat off the OEM specs (too low) with Dexron VI. Nevertheless, there shouldn't be any wear or damage concerns with Dexron VI.
 
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I also noticed that both DEXRON-III H (the last DEXRON-III specification) and DEXRON-VI require power-steering vane-pump wear test using ASTM D2882-00 Modified: 80 ± 3 ºC, 6.9 MPa, 3-gal canister, Conestoga pump parts. Both specs require less than 10 mg weight loss under this test. Requirement for DEXRON-III G and earlier is 15 mg or less weight loss. (See the Afton specification handbook [link].) Therefore, both DEXRON-III H (and earlier) and DEXRON-VI are designed and tested to be power-steering fluids. The only concern with DEXRON-VI is slight loss in power-steering assist due to lower pressure caused by lower viscosity. However, this will vary between ATF brands and all DEXRON (II and above) ATFs are designed to have a minimum sheared (used fluid) viscosity of 5.5 cSt or above.* Therefore, the differences between steering assist will be minimal if not negligible. I would definitely use DEXRON-VI instead of DEXRON-III H or earlier because its full or part synthetic nature and better antiwear/extreme-pressure/friction-modifier additives should lead to less power-steering vane pump wear and the fluid should last longer due to its higher-quality base oil. *Valvoline DEXRON-III H has 7.1 cSt viscosity at 100 C and Valvoline DEXRON-VI Full Synthetic has 6.0 cSt viscosity at 100 C. This corresponds to up to 15% less pressure and steering assist with DEXRON-VI with new fluids. However, part of the pressure is regulated through the flow-control valve in the pump and part of the steering effort is manual; so, after shearing effects (full synthetic will shear less leading to less viscosity loss), the difference between steering assist will probably be 5% or less, which is negligible.
 
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