What fluid should I use for automatic tranny?
 

My Lexus 2000 ES300 manual says to use ATF Type T-IV or Dexron III. Which is better?
Thanks.

Ahh it's Japanese. Just buy the first one you see in the store. Crap it'll run forever....

Tranny fluid. ;)

IMO Just use either, as long as you follow the manual the tranny should last longer than the rest of the car.

Any ATF that meets OR EXCEEDS those specs will do fine. I would buy full-synthetic (i.e. Amsoil ATF, or Redline ATF) as it is cheap insurance for such an expensive system.

I would love to put synthetic in there since I can easily find them at autozone, but I affraid it'll leak. I had bad experience with synthetic engine oil on old car. As far as deron III or IV, there only thing I can find is Walmart brand, which I affraid it's bad for the car. Am I worry too much? Any other place I can look for some decent Dexron III?

ok, what car & what does the owner's manual spec. for it?

many like redline, but it is synthetic IIRC

I'd avoid Walmart unless this is an old beater.

Crazy as this may sound to some, when I had the trans flush done to our Ranger, I asked about synthetic, since I'm a mobil 1 fan... The independent transmission shop I trust said to stick with standard fluid.

Oh, a flush removes all old fluid, replaces with new. Takes special pumping equipment. A "change" leaves a lot of fluid in the torque converter.

My '88 F250 used Dexron III. You should be able to find it at ANY autoparts store.
The fact that you're bothering to change the transmission fluid puts you miles ahead of most cars in america. I don't think it matters what brand you use.

Truth...most cars die from other ailments with the installed at the factory auto trans fluid in place...

Oh Hell, what's wrong with Wally Mart? They so big that they have suppliers provide them with anything and just add their name to the box or bottle. Do you think that Wally Mart ATF is any worse then Amsoil, or Shell, or Mobil? They all come from the same refinery.

ruf, I don't know. Most people don't trust Walmart brand. In fact, I heard multiple time that their engine oil is actually Valvoline oil. I tried it and it reacted different. According to a reputable mechanic, it was a good reaction. On tranny fluid, since it's not that easy to replace, I just want to pick the right fluid and hear opinions so I don't have to get under there again soon.

Thats easy - For your Lexus - use Toyota Type T IV ATF fluids.

Most domestic history: Tranny fluids can be divied into two major groups - those that contain friction modifiers and those that do not. Friction mods are chemicals that make the fluid more slippery under certain conditions. Until the mid 70's, Ford produced trannys with small frictional surfaces. The bands and clutches had to be applied quickly with high pressure to prevent over heating and wear caused by excessive slippage - this requires a non-friction modified fluid with a higher static of coeefficient of friction than a dynamic coeeficient of friction - in other words the frictional forces between the clutches and bands are greater when there is no reletive motion between the components then when they are slidiong against one another before lock-up AKA the hard shift.
GM trannys require a more slippery fluid to permirt a smooth shift without any shudder. When the clutch or band locks ups, the friction mods react to decrease the coefficient of dynamic friction - this allows the use of low clutch and band pressures and more plates in the clutch packs to prevent excessive slippage and heat build-up.

Using the wrong fluid in either tranny style will result in poor shift quality and short component life.

For Ford model years, use the following spec's fluids:
1949-1960: Type A
1960-1981: Type F
1977-1981: Type CJ
1982-1987: Type H
1988-1992: Mercon
1992-present: Mercon Revised
1997-present: Mercon V

For GM model years, use the following spec's fluids:
1949-1966: Type A
1967-1973: Dexron
1974-1991: Dexron II/IID
1992-1994: Dexron IIE
1995-present: Dexron III

For Chrysler model years, use the following spec's fluids:
Pre 1988: Dexron IID
1988-1997: ATF Plus, ATF +2
1998 - Present: ATF+3
1999 - Present: ATF +4

LubeMaster,
wow... worth the wait. Thanks. Can I dig your well knowleage brain one more question?
For an automatic Lexus with 110k miles, do you think it's better to use Toyota Type T IV ATF fluids or better to use Dexron III (also recommended in the manual)?

Mike, you're a super-smart guy, but I hope you don't really believe that list is gospel. I wish it were as simple as looking at your list, finding your year, and using that fluid. There are so many contradictions and footnotes that have to be considered.

For example, 2004-2007 Saturn V6 VUEs used a Honda V6 and Hondas (horrible) clutch-to-clutch Aisin-type automatic. 2002-2007 Saturn 4 cyl VUEs if they were AWD used a CVT transmission. If I owned, say, a 2007 Saturn VUE (because it has a GM badge right there on the fender), I'd look at your chart and fill it with Dexron III. It would ruin the CVT, quickly. The Honda unit would likely fail too, if it wouldn't anyway.

For example, my 2007 Ford F250 Diesel specifies Mercon SP, and says NOT to use Mercon V. For example my 2005 Lincoln Navigator has a ZF 6spd auto trans, not Ford, and does not use Mercon V.

If it were only that simple.

Check your owner's manual.