Hello all,
This is my very first ATF UOA on this vehicle and ever in my life. After receiving the results, I was surprised. Despite the UOA being great accompanied by the suggestion to run the fluid for another 20k miles, I decided to do a complete cooler line fluid exchange yesterday with Idemitsu TLS-LV which is a well-loved synthetic, legit WS fluid. Although the MaxLife performed decently enough, I LOVE the TLS-LV so much more. The shifts are much smoother and it's profoundly noticeable that the viscosity and the friction modification package is very different from the ML which is recommended for use with WS applications but isn't actually a dedicated WS fluid. I wish that I had installed TLS-LV much sooner and it will be my preferred fluid of choice going forward. The following is the letter that I included with the sample when it was sent to Blackstone. It includes detailed information about the history, usage, and driving characteristics of the car at the time of sampling:
Dear Awesome Lab Technician,
I bought this car in 2017 with 58,000mi on it. This AT is an Aisin U341E which calls for Toyota WS ATF. I don’t have any evidence suggesting the fluid was changed before I got the car. I did a complete fluid exchange at that time using Valvoline MaxLife ATF. I did not change the filter or drop the pan. The old fluid was pumped out of the unit’s cooler line and new fluid was poured into the dipstick tube until the fluid coming out of the cooler line was bright, clear, cherry red like the new fluid. Unfortunately, the old fluid was not tested at the time. It was a dark blackish-purplish like almost all WS factory fills after 60k+ miles. At that time, I also installed an ATF cooler. It is a Tru-Cool LPD4542 fin & plate cooler. The company claims to have designed the cooler’s cross tubes to effect automatic fluid bypass when the fluid is not yet at operating temp. Because of that, I do not have a fluid thermostat installed. Here in Southern AZ our summers are routinely between 100*F and 115*F for 4 or 5 months every year and my city has no major East-West highway so traveling across town is often in stop-go traffic at speeds between 30-45mph for 30-45 minutes. I figured the AT would benefit from a cooler in those brutal conditions. In the summer, I have never seen it go above 85*C when using a pan temp sensor PID with the TorquePro app. The fluid leaves the AT and passes through the factory ATF cooler loop in the radiator tank, and then it enters the aux cooler and returns back to the unit. The cooler is mounted to the condenser in a traditional way. I installed the cooler first and then did the fluid exchange, such that the old fluid was pumped out through the cooler to “flush” any residual solvents or debris that may have been present inside.
This MaxLife fluid has always shifted a bit firm and clunky. In the cold winter weather, it’s much more pronounced. The first few shifts in the cold morning are definitely noticeable. I am basically concerned about moisture, wear metals, and clutch wear. My fears are that:
I am considering changing to a different ATF and I am undecided on what to do. I heard that Toyota changed the WS fluid composition and it’s different now. I hear “WS is not synthetic and it’s hygroscopic trash” as well as “Of course they say it’s WS compatible, they’re the ones who make it! Only use the fluid that the engineers designed for it.” What is your professional opinion on these Aisin units from the early 2010s? Do you have a preferred WS spec fluid that you see performing well in your labs?
Thanks! -Manny
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TL;DR The only unique factor for this test is that this unit does have a 7,500 BTU aux cooler installed. With a full flush via cooler line, the factory fill WS was replaced with Valvoline ML in 2017 at 58k miles. The ML was tested by Blackstone in 2024 and was still serviceable 30k miles later, but it had always shifted hard and clunky and it was worse in the cold weather. The ML was flushed via cooler line very shortly after the test with Idemitsu TLS-LV and the shifting performance is dramatically improved. The ML is not an official WS fluid whereas the TLS-LV is. The unit now has 88k miles on it as of the time of writing.
I think the most important thing most of you will care about seeing is that the ML does not appear to have done any damage at all over the course of these 30k miles of severe service operation in a very hot, dusty, mixed city/highway environment including lots of short tripping and lead foot driving. The fear of most is that the ML will damage a WS unit, and through my experience and testing I conclude that there will be no abnormal damage in the short term and at most the worst effect is firm, clunky shifts as a result of friction modifier package differences and a higher viscosity than WS. I can't speak on the possibility that ML will cause accelerated friction material wear as a result of the FM package difference over the course of a much longer period of 100-200k miles, but it seems reasonable that we can conclude in the short term that a 30k mile OCI won't cause any unusual or accelerated wear.
This is my very first ATF UOA on this vehicle and ever in my life. After receiving the results, I was surprised. Despite the UOA being great accompanied by the suggestion to run the fluid for another 20k miles, I decided to do a complete cooler line fluid exchange yesterday with Idemitsu TLS-LV which is a well-loved synthetic, legit WS fluid. Although the MaxLife performed decently enough, I LOVE the TLS-LV so much more. The shifts are much smoother and it's profoundly noticeable that the viscosity and the friction modification package is very different from the ML which is recommended for use with WS applications but isn't actually a dedicated WS fluid. I wish that I had installed TLS-LV much sooner and it will be my preferred fluid of choice going forward. The following is the letter that I included with the sample when it was sent to Blackstone. It includes detailed information about the history, usage, and driving characteristics of the car at the time of sampling:
Dear Awesome Lab Technician,
I bought this car in 2017 with 58,000mi on it. This AT is an Aisin U341E which calls for Toyota WS ATF. I don’t have any evidence suggesting the fluid was changed before I got the car. I did a complete fluid exchange at that time using Valvoline MaxLife ATF. I did not change the filter or drop the pan. The old fluid was pumped out of the unit’s cooler line and new fluid was poured into the dipstick tube until the fluid coming out of the cooler line was bright, clear, cherry red like the new fluid. Unfortunately, the old fluid was not tested at the time. It was a dark blackish-purplish like almost all WS factory fills after 60k+ miles. At that time, I also installed an ATF cooler. It is a Tru-Cool LPD4542 fin & plate cooler. The company claims to have designed the cooler’s cross tubes to effect automatic fluid bypass when the fluid is not yet at operating temp. Because of that, I do not have a fluid thermostat installed. Here in Southern AZ our summers are routinely between 100*F and 115*F for 4 or 5 months every year and my city has no major East-West highway so traveling across town is often in stop-go traffic at speeds between 30-45mph for 30-45 minutes. I figured the AT would benefit from a cooler in those brutal conditions. In the summer, I have never seen it go above 85*C when using a pan temp sensor PID with the TorquePro app. The fluid leaves the AT and passes through the factory ATF cooler loop in the radiator tank, and then it enters the aux cooler and returns back to the unit. The cooler is mounted to the condenser in a traditional way. I installed the cooler first and then did the fluid exchange, such that the old fluid was pumped out through the cooler to “flush” any residual solvents or debris that may have been present inside.
This MaxLife fluid has always shifted a bit firm and clunky. In the cold winter weather, it’s much more pronounced. The first few shifts in the cold morning are definitely noticeable. I am basically concerned about moisture, wear metals, and clutch wear. My fears are that:
- I have over-cooled the fluid and moisture is built up because it can’t be boiled out while driving.
- The torque converter lockup solenoid in the valve body is PWM and my driving habits may be causing accelerated wear and tear.
- The TCC, clutch, and bands are wearing excessively from using non-OE non-WS fluid.
- The MaxLife is not close enough to WS spec and other unknown damage is occurring that I don’t anticipate.
I am considering changing to a different ATF and I am undecided on what to do. I heard that Toyota changed the WS fluid composition and it’s different now. I hear “WS is not synthetic and it’s hygroscopic trash” as well as “Of course they say it’s WS compatible, they’re the ones who make it! Only use the fluid that the engineers designed for it.” What is your professional opinion on these Aisin units from the early 2010s? Do you have a preferred WS spec fluid that you see performing well in your labs?
Thanks! -Manny
--------------------------------------------------------
TL;DR The only unique factor for this test is that this unit does have a 7,500 BTU aux cooler installed. With a full flush via cooler line, the factory fill WS was replaced with Valvoline ML in 2017 at 58k miles. The ML was tested by Blackstone in 2024 and was still serviceable 30k miles later, but it had always shifted hard and clunky and it was worse in the cold weather. The ML was flushed via cooler line very shortly after the test with Idemitsu TLS-LV and the shifting performance is dramatically improved. The ML is not an official WS fluid whereas the TLS-LV is. The unit now has 88k miles on it as of the time of writing.
I think the most important thing most of you will care about seeing is that the ML does not appear to have done any damage at all over the course of these 30k miles of severe service operation in a very hot, dusty, mixed city/highway environment including lots of short tripping and lead foot driving. The fear of most is that the ML will damage a WS unit, and through my experience and testing I conclude that there will be no abnormal damage in the short term and at most the worst effect is firm, clunky shifts as a result of friction modifier package differences and a higher viscosity than WS. I can't speak on the possibility that ML will cause accelerated friction material wear as a result of the FM package difference over the course of a much longer period of 100-200k miles, but it seems reasonable that we can conclude in the short term that a 30k mile OCI won't cause any unusual or accelerated wear.
