08 Prius ATF Analysis

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Md, USA
Blackstone Labs 31,365 miles on car and fluid Factory Fill No make up fluid This being the first ATF sample since the transmission was new, the higher-than-average metals and silicon are not surprising. Universal averages show typical wear levels for this type of transmission after about 19,600 miles on the oil. The elevated metals readings are from new parts wearing-in, as well as accumulated from normal use. Silicon is from sealers. The viscosity was a little light, likely from the long ATF use. The TAN reading of 1.6 shows the ATF was somewhat acidic. Check back after 20K miles on the next oil. ALUMINUM 46 CHROMIUM 3 IRON 103 COPPER 12 LEAD 1 TIN 3 MOLYBDENUM 1 NICKEL 6 MANGANESE 4 SILVER 0 TITANIUM 0 POTASSIUM 1 BORON 56 SILICON 184 SODIUM 3 CALCIUM 130 MAGNESIUM 3 PHOSPHORUS 282 ZINC 6 BARIUM 3 cSt Viscosity @ 100°C 42.7 SUS Viscosity @ 210°F 5.02 Flashpoint in °F 335 Fuel % Antifreeze % Water % Insolubles % TR TBN TAN 1.6 ISO Code I refilled with Redline D6, no noticeable change in performance.
 
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I wouldn't go more then 30k with any fluid. If anything, I would probably change it sooner. ~170ppm of wear in ~32k miles is a little steep for a single speed.
 
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RI
That 'cst' is only at 100c. Plus, the Redline will shear a little too. And, it probably has a better(less steep) visc curve meaning the MPG might actually improve. What is the capacity of the transmission vs. what comes out of a drain/refill?
 

montero1

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I got out just under 4 quarts, it took just under 4 to fill. I'm actually getting the best mileage I've ever gotten, 250 miles into a tank. In the summer, I can usually go 500 miles. Right now the computer is figuring 59.8 mpg.
 
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8,756
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RI
My Toyota has a 3.7 drain/refill capacity with 10+ quarts of ATF capacity. I get a <40% change out each time I drain/fill. I believe that the total capacity is ~4 quarts, so each Prius drain/refill is hopefully leaving only a couple ounces behind.
 

montero1

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1st tank since changing ATF: 544 miles, fill up with 8.77 gallons. MFD read 60.5 mpg, actual was 62mpg. Hands down the best I've ever gotten. I don't know if it'e the ATF change or not, but it sure is a coincidence......
 
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 Originally Posted By: montero1
1st tank since changing ATF: 544 miles, fill up with 8.77 gallons. MFD read 60.5 mpg, actual was 62mpg. Hands down the best I've ever gotten. I don't know if it'e the ATF change or not, but it sure is a coincidence......
Interesting. We know WS viscosity at 100C (from VOA/UOA). But we don't know the 40C and -40C numbers. D6 must be much better in that regard. This is interesting. WS was supposed to be low viscosity full synthetic fluid optimized for fuel efficiency, but at expense of diff protection (many owners of RAV4 and Highlander complain of front diff whine). Yet, looks like VI of WS may be nothing special. Is it really synthetic? Similarly, new Mobil 1 ATF multivehicle formula has much worse cold viscosity numbers than the old formula. Semisynthetic?
 
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8,756
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I doubt that any automaker has anything that is 'really synthetic'. GroupIII if we're lucky, and more then likely a low percentage blend at that. Some dealers charges <$5 a quart for WS. Can't be anything exotic there. MSDS's, VOAs, UOAs here, along with SAE(or Jaso) papers give you data if you're in need of it. Don't confuse data sheet numbers with formulas or performance. A pour point depressant, basestock, and/or VII/VM, change can change numbers around. I still believe M1 ATF is a full synth and am hoping that the spec change makes it more robust for the real world. Amsoil's -40c was never anything to brag about. But, its an excellent ATF.
 
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Just did the same change on my 2006 Prius--replacing WS with D6. Probably won't do an oil anal on the drained WS this time, having done one about 12,000 miles ago. Did notice what seemed to be an increase in engine rpm during initial acceleration when cold. This has now disappeared, and cannot tell any difference in performance from WS. We'll see how mpg is affected.
 

montero1

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Originally Posted By: friendly_jacek
Any follow-ups on the MPG change? I find it curious that MPG went up.
Last tank, 52mpg, though it has gotten cooler, rainy, and I've been making shorter trips since being out of work 10 weeks from back surgery. It may have been just a coincidence that I got my all-time best mpg right after the fluid change. Could be possible that putting fresh WS in would have given the same results.
 
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