Transmission Fluid - Synthetic or Conventional?

[Rusty Shackleford]

I'm going to be draining/replacing the transmission fluid soon, and was all set on switching over to Amsoil full synthetic, but I read a thread on here where another person was experiencing sloppy shifts and a sluggish feeling overall after switching from dino to synthetic, so he switched it back. Is this common?

What's the consensus on here - switch to synthetic, or keep it conventional? My truck has ~176k on it right now and it shifts flawlessly and the transmission feels very smooth. I don't want to switch it over and risk messing something up.

 

[ASUMTNEER]

Just stick with OEM fluid. It has obviously worked up until now.

 

[Rusty Shackleford]

Just stick with OEM fluid. It has obviously worked up until now.

That's kind of the direction I'm leaning now. The old "if it ain't broke, don't fix it" mantra

 

[Nunyabiz]

That is nonsense, there is never a real reason to go with anything other than Synthetic fluid today.

I switched ALL my fluids over to 100% synthetic at 157xxx miles when I bought it.
Oil, ATF, and all Gear lubes are all synthetic.

 

[LittleCaesar]

Most dealers I know don't even stock Dex III anymore. The most dated trans fluid they carry is most likely T-IV. If they need an older batch, they will usually get it from NAPA or whichever parts store they use in a pinch.

I'd chose either Castrol Import ATF or if the wallet is deep enough, Amsoil ATF.

 

[Rusty Shackleford]

That is nonsense, there is never a real reason to go with anything other than Synthetic fluid today.

I switched ALL my fluids over to 100% synthetic at 157xxx miles when I bought it.
Oil, ATF, and all Gear lubes are all synthetic.

Have you experienced any difference with the way your transmission feels or shifts?

A buddy of mine is an Amsoil dealer and he sells me everything at the price he gets it for, so it's definitely doable, as long as the switch to synthetic is worth it and doesn't cause me any issues.

 

[Tsfc]

What's up buddy, good on you for keeping up on the tranny maintenance.

The drain and fill in my opinion is the way to go, do a couple and you have all new fluid in there, as you know.

Toyota dealers do not keep anything but toyota oem SEMI-synthetic tran fluid on hand and in fact that is how they prep their new vehicles for sale on the floor. Not trying to steer you any way or the other, just saying that the toyota spec fluid is totally fine...keep in mind I live in a region which routinely reach -58f and below and that is how they prep even new vehicles and what they put in older vehicles coming in for service. No issues.

That said, fully syn dex should be totally fine as well, especially if you only changing a portion of the tran fluid at a time which is what occurs with a drain and fill.

Cheers and best of luck!

 

[Rusty Shackleford]

So if I go the synthetic route, how many quarts should I buy for the drain & fill?

 

[badattitude]

My 1999 takes 5.25 quarts of ATF with a drain and fill, some newer 4runners only take 2.5 on a drain and fill. Get 6 quarts to be safe. Make sure you get about 5 quarts out then put five quarts in and drive it around to warm it up and test the level on the dipstick. If you need a little more add it in.

 

[Rusty Shackleford]

My 1999 takes 5.25 quarts of ATF with a drain and fill, some newer 4runners only take 2.5 on a drain and fill. Get 6 quarts to be safe. Make sure you get about 5 quarts out then put five quarts in and drive it around to warm it up and test the level on the dipstick. If you need a little more add it in.

Great, thanks!

 

[ben550]

Just stick with OEM transmission fluid. I use non oem fluid for engine oil, power steering, differentials, transfer case, and brake fluid. I stick with oem for coolant and transmission fluid. Just seems safer for those components.

And I of course exercise great freedom with which window washer fluid i use... haha

 

[jgue467]

I had mine flushed at 177k w/full synth, then i drained/filled at 225k and again at 245k (climbed some mountains); no drips, runs or problems of any sort. Same for engine oil & all 3 diffs - full synth is just better. :banana:

 

[JEL]

I don't know if there is a need to stick with "oem" fluid, if by that everyone means Toyota brand DexIII ATF. You can simply use any Dex III ATF, last time I did a drain and fill (do it every 10-15k with conventional depending on use) I used Valvoline Dex III, before that I believe I used Chevron; no issues as long as they're both Dex III. The transmission is actually the only place I DON'T have synthetics in my 3rd gen (my 4th gen uses a factory syn, WS), I have no qualms switching to synthetic, but it's been fine for 200k so far with 15k drain and fills so that's probably what I'll just stick with to keep things nice and clean.

It took just under 5qt last time I did it, even though IIRC the manual said it was about 2qts.

 

[Tsfc]

my 1999 takes 5.25 quarts of atf with a drain and fill, some newer 4runners only take 2.5 on a drain and fill. Get 6 quarts to be safe. Make sure you get about 5 quarts out then put five quarts in and drive it around to warm it up and test the level on the dipstick. If you need a little more add it in.

.

+1!

 

[Nunyabiz]

Have you experienced any difference with the way your transmission feels or shifts?

A buddy of mine is an Amsoil dealer and he sells me everything at the price he gets it for, so it's definitely doable, as long as the switch to synthetic is worth it and doesn't cause me any issues.

I experienced zero issues, in fact have experienced zero issues using synthetic oil/ATF/gear lube since 1977 in every kind of engine, from 4 cylinder VWs to 6 cyl Fords, Honda, Porsche. 8 cyl Diesel, 6cyl Toyota.
Even my old Outboards, Lawn mowers, Pressure Washers, EVERY engine I have owned since 1977 has been running on the best 100% synthetic I could get my hands on with zero issues for 37 years.

I noticed no real difference in the 4Runner trans feel or shift, I do not have a Trans temp gauge but I would lay odds that it runs a bit cooler with the Synthetic ATF though, I know it protects better and last longer.

 

[Nunyabiz]

So if I go the synthetic route, how many quarts should I buy for the drain & fill?

IMO especially since yours has NEVER been changed then a drain & fill is virtually worthless.
I have never understood why anyone would take about 3-4 quarts of perfectly good ATF and mix it with old ATF.
When you change your oil would even think of doing that?
Drain like 2 quarts and add 2Qts to 4 quarts of oil with 5000+ miles on it?

You need about 12-14+ Quarts to do it properly.
Drop the pan, check the magnets, reseal it.
Then start pumping in fresh ATF 1 quart or so at a time until you see nothing but fresh ATF coming out.
Or take to a T-Tech machine.

Throwing 3-4 quarts of fresh good synthetic into thoroughly used ATF with 176K on it is a total waste of good ATF.

 

[I-4x4]

I just flushed my trans fluid and replaced it with Redline D4

I haven't noticed any major differences to be honest, except for the hole in my pocket.

Lower operating temps = longer transmission life in theory(c.p.)

^ That and synthetic lasts longer.

Just my two reasons for going synthetic.


I used 16 quarts for the flush.

 

[Rusty Shackleford]

IMO especially since yours has NEVER been changed then a drain & fill is virtually worthless.
I have never understood why anyone would take about 3-4 quarts of perfectly good ATF and mix it with old ATF.
When you change your oil would even think of doing that?
Drain like 2 quarts and add 2Qts to 4 quarts of oil with 5000+ miles on it?

You need about 12-14 Quarts to do it properly.
Drop the pan, check the magnets, reseal it.
Then start pumping in fresh ATF 1 quart or so at a time until you see nothing but fresh ATF coming out.
Or take to a T-Tech machine.

Throwing 3-4 quarts of fresh good synthetic into thoroughly used ATF with 176K on it is a total waste of good ATF.

Thanks for all of your feedback and advice. Honestly, I can't say that my ATF has never been changed, it just hasn't been changed by me. I checked the fluid and it didn't really look that bad, but that was just what was on the dipstick. I'm still up in the air about whether to attempt it myself, or just let my local shop do it. They're very reputable and their work is warrantied, mine isn't.

 

[Nunyabiz]

Thanks for all of your feedback and advice. Honestly, I can't say that my ATF has never been changed, it just hasn't been changed by me. I checked the fluid and it didn't really look that bad, but that was just what was on the dipstick. I'm still up in the air about whether to attempt it myself, or just let my local shop do it. They're very reputable and their work is warrantied, mine isn't.

If you do not do it yourself then get someone with a "T-Tech" machine to do it.
Here is some 10 minute oil change place near you that has one supposedly.
I would just bring your own ATF like the Amsoil, probably take at least 14 Quarts, I think it actually takes about 11 Quarts but usually takes a few quarts extra to flush it all through and get all clean, bright red, fresh fluid coming out.

https://www.facebook.com/pages/Pennzoil-10-Minute-Oil-Change/308517629194906

 

[AZ4Running]

Valvoline Max Life ATF fluid is really good stuff. Its is full synthetic and works with just about every AT out there aside from CVT but we dont care about those here. Max Life meats all
DEX and Merc requirements. Our Toyotas need Dex3 fluid if i remember correctly.