DroLs400

Hey so first time changing out my oil and for some reason google and a lot of other people on these forums recommend Dexron iii but a lot of people fighting that type t IV is the best…. I know I could probably use either but over time I know one is definitely better. Especially because I drive my car every day and trust me I floor it a lot. Runs like a champ but don’t think it’s even had it’s fluid changed before. Also see a lot of people saying mobil 3309 is exactly the same fluid as the Toyota type IV but also I know a lot has changed since 1998 and all the years passing… has anything changed?? Is the Toyota Type T really the best nowadays? I know it’s definitely safe but has it been surpassed?

bradland

With ATF it's not a question of quality or which fluid is better. Dex III or any modern iteration Dexron V, VI, etc is sold by a variety of companies so "quality" can vary.
Toyota T-IV is the "correct" fluid for your Aisin transmission because the additive package (friction modifiers) is unique from other types of ATF.
Yes, 3309 is the same as T-IV.

400fanboy

The transmission hardware is still 25+ years old, and may not be able to take advantage of the improvements in the new formulations. So new fluids can have improved characteristics, and many do, but you need the other side of the equation as well. Your box is still expecting a specific blend and is optimized to work with exactly that.

If you want better performance or are adding more power to your car, then of course everything changes. Different fluids may be necessary.

My previous car was a 2006 Honda accord with a manual transmission. Honda gearboxes are great, the shift feel is among the best and I really enjoy how they calibrate them. But, many of them like to grind on specific gear changes. My particular car would sometimes grind going into third gear. And sometimes it wouldn't seat at all and would pop out. It was a defect with the gearset itself. You had two choices:

1) pull the transmission and replace the gear at who knows what expense
2) use GM Syncromesh transmission fluid. Yes, *that* General Motors. V6 motors have a 2-3 shift, i4 motors (S2000 & others) have a 1-2 shift where using this fluid helps.

And by help, I mean completely solves the problem. I drove 40,000 miles where it never happened again. We don't know what the long-term potential lifetime damage the different fluid causes. But whatever it is, it sure as **** is less-worse than grinding third gear on average every 10 gear shifts.

The point of this story is - there are solutions to where putting different fluid in can work - but really only when solving a specific problem. Otherwise - stick with what the engineers who designed the transmission specify.

LeX2K

No one every takes my advice on this but I'll try anyway, this is by far the best ATF to replace Dexron and T-IV.
https://www.amsoil.com/p/oe-multi-ve...ion-fluid-otf/

Doing this means you are running fluid using technology that is decades old.

paulo57509

For a DIY, unless T-IV becomes unobtanium there is reason to switch to something else. Idemitsu T-IV, Modil 3309, Aisin T-IV or Toyota T-IV are all still available.

I'm not a fan of one-fluid-fits-all. YMMV

LeX2K

That's because you have not tried Amsoil once you do you'll never go back.

Modil 3309 is T-IV they are identical.
Of course there is, lubricant technology has improved immensely in 20+ years.

400fanboy

Alright I'm open to learn something then. These specifications of librisoty define viscosity and all of these other characteristics, that if the transmission oil meets or exceeds, it can be defined as "suitable for this SAE specification".

Obviously things have moved on in the last 30 years.

Is it really as simple as "must meet or exceeded these specific parameters", and if the oil does, then it's a suitable replacement presuming it's weight rating is the same? Hence the Amsoil blend you suggest? Do you have literature on this subject? Oils is a maddenly complex subject, but with very little information or resources to learn actually what is going on. And actually what oil is suitable for a given application.

LeX2K

I've used the above Amsoil in many cars including my own, it is outstanding. Also great for PS systems that call for Dexron. It even makes the crappy U140E in my Lexus shift properly something it will never do running 3309. It also does not darken nearly as quickly as the OE stuff.

I don't recommend it for applications that call for Toyota WS, for that use case go with Amsoil Signature. But that's just my experience, go with what you're comfortable with.