ATF Change Before & After Photos

2008 T4R V8 4WD Limited with 40,275 miles (about 5,000 of which were towing a 4,800-pound camper). It was bought new with less than 25 original miles from the local Toyota dealership.

I had a complete ATF exchange at a local reputible shop today and I asked him for a sample of the original fluid they removed so I could inpsect it and compare it to new. Here is a photo showing clean new fluid on top with the Toyota WS fluid with a little over 40,000 miles on it. I'll let you draw your own conclusions about the "lifetime" transmission fluid in your 4th generation T4Rs.

https://lh6.googleusercontent.com/-Ntk_zbCHPrk/TinrO81p-3I/AAAAAAAADmE/z55gG-mduJM/s144/IMG_6274.JPG

I will be changing my ATF every 40,000 - 50,000 miles, even after converting to 100% synthetic Wolf's Head ATF, which is compatible with the Toyota WS fluid. Cost me $272.33, well worth it to keep that tranny running strong and smooth.

If you're that hard on your transmission fluid, you should install an auxiliary transmission fluid cooler.

If you're that hard on your transmission fluid, you should install an auxiliary transmission fluid cooler.

Well, I believe the vehicle is equipped with a transmission cooler, having the tow package. I sent a sample of the Toyota WS ATF into Petroleum Technologies Group for analysis and their comments are:
"All elements are acceptable. The oil is reusable. If reused
please resample at normal interval".

Oxidation is 14, water % is less than .1, no antifreeze, no soot.

Particle count is:
4 micron: 0
6 micron: 441
10 micron: 25
14 micron: 11
25 micron: 6
50 micron: 4
100 micron: 0.

The ASTM Viscosity @100C is 0.0 and @ 40C is 23.6 (I presume this is in cSt, but it doesn't list units). From what I could gather on the web, the viscosity of new WS ATF is 6 cSt @ 100C and 25 @ 40C. So it seems I may have lost a little bit it of viscosity, especially at higher temps.

So perhaps a second tranny cooler would be of help? Where exactly and how would this be mounted and tied into the OEM tranny cooler?

Thanks for the input.

Normally they are mounted in front of the radiator in the fan airflow. They are run in series with the existing transmission cooler line that goes into the bottom of your radiator, after the fluid exits the radiator cooler. If you want to, you can use a dedicated temperature-controlled fan and mount it out of the radiator airflow in a cooler area. Mounting is different for each truck, where you have to match the tubing size of the existing cooler lines.

Coolers are normally rated by Gross Vehicle Weight. If you have a mid-sized truck and tow 5,000 lbs, then you would get a cooler with GVW rating of 18,000 to 24,000 lbs. An SUV towing up to 7,500 lbs, you would get a cooler with a GVW rating of 22,000 to 26,000 lbs.

ref. http://www.bulkpart.com/transmission-cooler.html

http://www.grandprix.net/upgrades/cooler.html

I checked my 4Runner last night and it does have an auxiliary tranny cooler mounted just in front of the radiator on the driver's side. The lines run through the radiator as well.

I contacted the lab that ran the analysis and they re-tested the fluid for viscosity:
23.6 cSt @ 40C
6.4 cSt @ 100C (they hadn't tested the viscosity at 100C previously)

I spoke with Toyota and the viscosity of their WS ATF is:
23 cSt @ 40C
5.45 cSt @ 100C

So it looks like the fluid properties were still good. If not for the discoloration and very slight "burnt" smell, I'd say the tranny fluid was pristine.

Still, I will have the new Wolf's Head Universal ATF re-tested once it reaches 30k miles, just to be safe.