ATF Oil temp light came on, drain and fill or flush?

[Supermoney]

So two things.

Newish to me 4Runner had its ATF oil temp light come on while going up a steep trail for about 5-10 miles. It came on just as we reached the top and that is where I shut it down and let it sit for a good 4 hours until we got back. The way home I took it easy but it was all down hill so wasn't putting much stress on it. The light never came back on and it has shifted 100% fine since then.

But my question is:

1) If the transmission is filled with regular Toyota ATF fluid, if I drain 6 qts and put in 6 qts of synthetic....would that cause problems with the fluids not mixing correctly or the regular ATF canceling out the synthetic?

2) because the temp light came on, should I just opt for a full flush and then re-fill with 100% synthetic?


One more thing, can anyone confirm, the rear diff is 3qts, front diff is 1.5qts and TC is 1.5qts? I plan on changing all those with synthetic

Thanks

 

[3bears]

Yikes
I would do a full flush
add an external cooler

lots of opinions on brands and if in series or not

but def a full flush, if that light came on , the fluid is toast

 

[alumarine]

The manual recommends letting it idle in neutral to cool the transmission down if the atf temp light comes on.

If it only happened once it's not the end of the world.

An external cooler would be a good idea if the vehicle is used this way.

Was it in 4hi or 4lo?

 

[FrankieJoe14]

Rear Diff:
w/o Diff. lock: 2.45 liters (2.59 US qts., 2.16 lmp.qts)
w/ Diff. lock: 2.75 liters (2.91 US qts., 2.42 lmp.qts)

Transfer:
Capacity: 1.2 liters (1.3 US qts, 1.1 Imp. qts)

Front
Capacity: 1.15 liters (1.22 US qts, 1.01 lmp.qts)

 

[mtbtim]

Supposedly, that ATF temp light comes on if you reach 300 degrees F. That means your fluid is completely cooked. I would not drive it until you do a full flush of your fluid.

Doing a full flush isn't complicated either. You just need one person to turn the truck on and off you while you're using the trans pump to flush the old fluid out one quart at a time.

Here's a video [MENTION=102606]infamousRNR[/MENTION] and I did doing a full flush for member [MENTION=110858]JoeBand[/MENTION].

<iframe width="560" height="315" src="https://www.youtube.com/embed/RumPXivBlk8" frameborder="0" allowfullscreen></iframe>

And, after this experience, I would highly suggest adding an external cooler in series with the stock cooler in the radiator. Here's a video for the install if you choose to do it.

<iframe width="560" height="315" src="https://www.youtube.com/embed/2nVbwe2t2T8" frameborder="0" allowfullscreen></iframe>

Finally, I'd suggest monitoring your trans temps somehow, either with a scan gauge or an OBDII bluetooth reader with an app like Torque Pro. Because, even with an extra cooler, you can spike your temps so it's good to keep an eye on it while you're pushing your rig hard. This way you can stop and let your trans cool off when it starts getting way up there.

 

[rudogg760]

what about his question about mixing synthetic and nonsyntetic atf? id like to do drain and fills every motor oil change.

 

[mtbtim]

what about his question about mixing synthetic and nonsyntetic atf? id like to do drain and fills every motor oil change.

Don't know if it would be advisable to mix them. I would have to say no, it's probably not a good idea. If I were going to switch to synthetic, I'd do a full flush so you get most of the conventional ATF out. I'd run at least 12 quarts through because that's the capacity of our transmission but probably better to go a little more like 14 quarts and call it good.

 

[rudogg760]

Don't know if it would be advisable to mix them. I would have to say no, it's probably not a good idea. If I were going to switch to synthetic, I'd do a full flush so you get most of the conventional ATF out. I'd run at least 12 quarts through because that's the capacity of our transmission but probably better to go a little more like 14 quarts and call it good.

it just seems like the tranny fluid hasnt been changed in so long. i dont want to do a full system flush and then it start slipping :/ ive had it since about march and i recently put in a tranny cooler and the atf was nasty looking

 

[Supermoney]

Thanks everyone I appreciate the help and information. I am going to have the trans flushed at Toyota on Tuesday. I don't think they will fill with synthetic as they only use Toyota ATF but that is fine and at least I will know when it was done and be able to drain and fill myself from now on using it.

If the trans starts to experience problems after the flush then I do have a extra trans out of my 01 that I will have thrown in if I have to.

Will report back.

 

[St Runner]

I will second getting a way to monitor temperatures. Knowledge is the best mod there is!