02 Tacoma 5VZFE A340F Transmission High Mileage Maintenance Assistance

I have a 02 Tacoma automatic with the A340F transmission. I bought it used and had the top half of the engine rebuilt and on my journey of dialing it in, I need to focus on my transmission and need some input or resources. Essentially I have no service history related to the transmission and did a drain and fill about 6 months ago. They said it was dirty but not extremely. Truck runs great so no issues or anything now. I'm going to be installing a Hayden 699 cooler in-series with a derale thermal bypass and a reybestos filter along with a trans temp sensor so I can monitor going forward. I live next to the Rockies and sometimes do long road trips with heavy loads but mostly daily driver that takes me everywhere I want to go.

What I'm looking to learn about:
What is the best way to get my fluid and transmission back to optimal conditions?
...
Yearly drain and refills (~10k miles per year)?
Dain and refill at longer intervals?
Do less volume changes but higher intervals?
Only use type IV fluid?
Should I drain, measure the amount taken out, then fill with the same amount of new fluid?
Since I'm replacing my soft lines with the filter, cooler, etc I will need to add fluid, if I've only driven 3-4k miles since last D/F, should I just do another D/F? Maybe too soon.
Aisin type iv good?

I don't know what I don't know when it comes to transmissions, and I want to know more so I can make an optimal plan to nurse my transmission back to optimal conditions as best as possible.

 

IIRC, v6 auto use dex2 and not IV. The drain bolt or the dip stick will indicate which atf type. Or run Val MaxLife, which is compatible with both.

I drain and fill the ATF annually, regardless of mileage. Mine gets about 1k hard miles each year. A gallon is ~25 buck which is cheap enough.

 

Ugh
Do some searching
HUGE internet 50/50 debate on this exact topic

-don’t do anything bc of transmission clutch material in fluid
—flush everything now
-change a small amt at a time over a period of time

 

How many miles on your Tacoma?

 

Yep, huge debate on this, people are entrenched in their positions and there are good arguments in both camps. IMHO, whatever wear there is is already there and what we are trying to avoid is further damage with contaminated/burned/worn out fluid. I am in the slowly replace the fluid over a period of time camp. ATF is a detergent fluid and again, just my opinion, a sudden inrush of fresh clean detergent only loosens the varnish and clutch material, if present and puts it in the pan.

Blow through the new trans filter before you install it... just had a buddy drop $20k bullet profing his Ford 6.0 and he had the shop put an auxilary trans cooler on while it was there. Truck didnt make it 10 miles before the trans started slipping, the new cooler was defective and had next to zero flow.

 

I got my truck as a restore project with 255k. Had to put a engine in it right away among countless other things.

At about 260k I started doing A/T pan drain and fills with valvoline maxlife with the 3k to 5k regular OCI. To get to 5. I have 280k now way smoother daily operation. Seems like my tranny is solid. I chose this route instead of flush. I did it 5x. You usually get about 2 plus qts each time measured and same amount returned.

 

I've done as much as I can and lots of differing opinions. A Toyota shop I trust said the recent change is fine for now and just change occasionally. I won't do a flush and it seems general advice outside a flush is just more frequent changes. It seems like no matter what I choose to do, there will be people thinking that's not the right thing to do.

240k

 

Thanks, good point. The manual says dexron II but from my research type IV is meant for this. Didn't know about Valvoline max life so thanks for bringing that to my attention and it's good to hear it could work regardless of what's in there. I know DII and T-IV can't be combined as they aren't compatible. I'll talk to the shop that did the recent change and confirm what they used. I saw there was a TSB that talked about type IV superceding dexron ii, but I don't feel confident in my understanding of everything so I'll defer to shop before I hook everything up. I was hoping to have it all hooked up so the shop could check it when I bring it in tomorrow but I'll hold off until I confirm with them the fluid that was used. Maybe they won't charge that much to just connect the lines (already routed and ready to be plugged in) and then top off fluid.
This will be a new routine maintenance task for me and I still need to learn more before feeling comfortable doing it myself. Trying to avoid costly fixes not create any haha.

 

Thanks for that info. I wasn't even considering a flush as it's way too much for me to risk given no known history other than recent drain/fill. And another recommendation for Valvoline max life which I appreciate. That wasn't on my radar as something I should use since it's not from Toyota.

 

Yeah totally understand what you’re finding

For what it’s worth
I was really leaning towards a flush from the tranny cooler hoses for multiple vids I watched. Then saw just how much tranny fluid needed. At the time, I couldn’t afford the fluid cost. One vid showed lil less of a 5gal bucket needed.
Then the clutch material thing

I decided to change pan fluid
Wait a month or two and repeat

I.E.
Gradually RR fluid over period of time
Not ‘shocking’ the system with a complete $$ flush

my opinion…..not stating this is THE way to accomplish
GL

 

Thanks, seems like that's a good way to go given research and some responses. The external Hayden cooler, thermal bypass and reybestos filter should help maintain it as well. Fingers crossed.

 

After talking to Toyota dealership and Toyota repair shop, they said dexron III compatible is what I need, of any type. Toyota said they don't have a branded dexIII so anything aftermarket works.

 

I’ll say I said so, lol

Valoline Maxlife (red bottle) is compatible

 

FWIW, I use Dexron 3 High Milage from Oreilly with addition of a little Lucas High Milage Oil Stabilizer and typically once every 1-2 years just drain the pan and add the same about back in (of course, since I'm lazy and hate finding the proper operating fluid level with that ridiculously long dip stick), also dropped the pan when I first got her and replaced the filter, my tranny is smooth, no issues.

https://www.oreillyauto.com/detail/...truck-2000-toyota-tacoma?q=transmission+fluid
https://www.oreillyauto.com/detail/...-truck-2000-toyota-tacoma?q=lucas+high+milage

Note, I put like an ounce or two of that Lucas product in for every quart of fluid...