Hi guys,

After a lot of reading and going down rabbit holes regarding ATF here, I reluctantly need to post for a somewhat straight opinion on my ATF.

I bought a 2001 2wd with 188k miles. What ATF is inside is totally unknown, and was overfilled. That being said the truck seems to shift fine. I did a transmission pan drain and a radiator/hose drain of ATF in the process of changing my radiator out, so I'm now short on fluid. Here comes the hard part:

Not knowing what fluid is in there, what is the smartest or safest choice?

1- Top off to factory levels with new Toyota T-IV, which I already procured but am now getting cold feet about mixing with whatever is in there. Perhaps without reason.

2- Top off with Valvoline Maxlife Synthetic, which I would have assumed is a no-no, but then again who know what's in there, that could even be synthetic.

3- Do a full "flush" via radiator line drain and topping off while running the engine, using Valvoline. In this case I'd have all the same ATF in the car, but I read about risk of transmission slip vs the pan drain method every 10-15k?

Thanks in advance! I don't want or mean to ignite a debate, but am hoping one of these is somewhat clearly a "safe" option

I would do option 3.

The stories of transmissions slipping after a fluid change/exchange was not because there was new fluid, the damage was already there. If you are concerned about the fluid that is in your tranny now, I would just exchange it out.

I, and many others on here have used Valvoline max life with good success. The 3rd gen transmissions are pretty bomb proof although the 01/02 years are a little more prone to failure.

Also, how does the mystery fluid look? Is it black? Does is smell burnt? If it doesn't look terrible I would have no hesitation doing a full fluid exchange.

Good luck.

I agree with gripper. Do not use t4 it will slip in your transmission. Use Vaseline maxlife. It's all I use in all my toyotas.

Or use t2 or t3...or other fluids mentioned in this forum that work.


I may have missed it. I pull the pan and change the filter along with cleaning the magnets.

Then I exchange via the radiator cooling hoses with a pump to pump the new fluid in. You can find it under the Brillo bucket fluid exchanger in my signature.

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I don't know where you've got your information to have the concerns you have. You have to assume whatever ATF is currently in the system is compatible with the original Dexron 3 spec. You can mix fluids as long as both were made to cover the Dexron 3 spec. Valvoline Maxlife is what I've been using for a while. I use to run a Dex/Merc. If you want to renew the whole system and start fresh, I have a video you can use.

Transmission Fluid Flush - YouTube

Thanks guys! This gives me a clear (and logical) direction to move in.

Old fluid is getting a better look tonight when I empty the drain pan, but at a glance when I drained it things seemed to be normal but "old", just a dirty dark red.

I'll report back once getting into it Friday!

Special shout out to you @mtbtim , who my wife has now labelled the most frequently used voice in our household after I consumed your TB videos over and over before tackling the job. Thanks!