Two or 3 weeks ago, I drained my '06 Camry transmission pan's T-IV ATF and
refilled it with Mobil 1 Synthetic ATF, making the ATF fluid in my
Camry a 50/50 mix of Toyota T-IV and Mobil 1 ATF.

My goodness, you're not going to believe this. Toyota recommends T-IV
fluid *AND* ATF WS fluid for the exact same automatic transmission,
depending upon Camry model year.



The 4-cylinder 2005 and 2006 Camrys have the Aisin U250E transmission,
whereas the V6 Camrys have the U151E.



One year later for 2007, the newly styled "next generation" Camry with
4 cylinders (same 2AZ-FE engine as the 2006) also uses the U250E
transmission, but instead of T-IV, Toyota specifies ATF WS for the '07
model year!



So here we have the two exact same transmissions, the U250E, but Toyota
specs T-IV in the 2006 model year, and specs WS in the 2007 model year.
The two fluids are not suppose to be interchangeable.



Here's a quote from GearsMagazine:

"One very important thing to remember is that the U250E requires
ATF WS:



"ATF WS is used to reduce the resistance of the ATF and improve the fuel
economy by reducing its viscosity at normal operating temperatures. At
higher fluid temperatures, the viscosity is the same as that of ATF Type
T-IV, which ensures the durability of this unit.



"ATF WS and other types of ATF (ATF Type T-IV, D-II) aren't
interchangeable. So with ATF WS you get improved fuel economy and
durability and that's not only smart... it's street smart!"[End quote]



Here's the link to the article in GearsMagazine.com :

http://74.125.45.132/search?q=cache:...&ct=clnk&gl=us

And here's a link to TransTec which verifies that the U250E is used in
both the '06 and '07 Camrys.

http://transtec.com/selector_guide/Toyota.htm



Finally, if you find it difficult to believe that the U250E transmission
in the '06 Camry and the '07 Camry is the EXACT same transmission, check
out this really convincing PDF document that shows the gear ratios, fluid
capacity, and weight of the transmissions in both the '06 and '07 Camry:

http://www.google.com/url?sa=t&sourc...3HJ53uSZ77sa_Q

Both the '06 and '07 transmissions weigh the very same 205 pounds, according to the above document. Not one pound difference, so I doubt any minor revisions were made at all. Even minor revisions could be expected to yield a pound or two difference, and probably a lot more.



My '06 owner's manual specifies using T-IV, but I also happen to have a
manual for the next gen. Camry (in this case the '08), and it specifies WS.



By the way, the next gen. 2007 V6 Camry uses that newer U660E

transmission ;-)


A couple weeks ago, I replaced half of my car's T-IV with Mobil 1
Synthetic ATF, but maybe a WS fluid would work just as well? Whaddya
think? Should I buy a WS or a T-IV replacement for my next fluid change
later this week? If a WS, I'll do an ATF oil cooler line complete flush,
instead of just a drain-and-fill. Either way, I'll DIY it (Do It Yourself,
of course).



For the U250E transmission, how can Toyota recommend two very different
ATF fluids that are not suppose to be interchangeable?
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