Transaxle Oil Analysis

[Bill Lumbergh]

I used a pump like this. It's easier and potentially less messy than a long funnel. They can be found at nearly every auto parts store.

[patsparks]

I used a 700mm length of 8mm ID tube and the top half of a clean dry water bottle and cap. I drilled a 10.5mm hole in the bottle cap and forced the hose into it to form a funnel then used the directions above. When finished I throw away the bottle after wiping it off, I seal the hose with 2 8mm bolts to keep it clean inside ready for next use.

I purchased the oil from Toyota in a 4 litre tin, my trans took the full 4 litres with no spillage. If I put my little finger in the hole I got oil on my finger when I bent it down. I reused the washers.

[edthefox5]

Originally Posted by dogfriend

I think its probably best to stay with WS ATF for the 2004 -08 transaxle. Besides the lube properties, there are (di)electric properties of the fluid which are important for the HSD transaxle.

Hi,
There are no dielectric properties to the WS ATF.Please stop perpetuating this Internet myth. It is simply a low viscosity ATF fluid with good anti-shear properties. There is nothing added to this fluid to make it compatible to the "windings" because the motor windings insulation covering is extremely strong and will not fail under normal use. You would have to go at the windings pretty good with a file to hit conductive material. How many failed windings have we seen on the entire generation of Prius? Very very few. You could probably run this trans on 3 in 1 oil. Toyota Engineering is not the slightest bit concerned about this insulation failing or they would have built a special fluid...and it would be very well known as a special fluid with certain lower mileage re-fill rates. Instead the dealer touts a 100K trans refill. What does that tell you about how special this fluid is?

[apriusfan]

Originally Posted by edthefox5

Hi,
There are no dielectric properties to the WS ATF.Please stop perpetuating this Internet myth. It is simply a low viscosity ATF fluid with good anti-shear properties. There is nothing added to this fluid to make it compatible to the "windings" because the motor windings insulation covering is extremely strong and will not fail under normal use. You would have to go at the windings pretty good with a file to hit conductive material. How many failed windings have we seen on the entire generation of Prius? Very very few. You could probably run this trans on 3 in 1 oil. Toyota Engineering is not the slightest bit concerned about this insulation failing or they would have built a special fluid...and it would be very well known as a special fluid with certain lower mileage re-fill rates. Instead the dealer touts a 100K trans refill. What does that tell you about how special this fluid is?

I wasn't aware of dielectric properties of the WS oil. However, I don't think I would go to the extreme of using some other oil as a cost-saving measure (penny-wise, pound-foolish). I am not a lubrication engineer, but if the WS oil could be swapped for another oil, the aftermarket companies (redline, amsoil, and, and, and) would be all over the opportunity.

[bwilson4web]

Originally Posted by edthefox5

Hi,
There are no dielectric properties to the WS ATF. ...

Not in the new oil but my concern has always been what happens in service. Unlike transformer oil that is not exposed to mechanical wear, our transaxle oil does age in ways that can be detected and predicted by oil analysis and in severe cases, direct observation:

• conductive particles - these seem to increase and come from the various parts that mesh together.
• Unknown additive properties - some of the oil additives have electrical properties, especially the metal based ones. Dielectric testing would be a reasonable thing to do to virgin samples just to make sure we don't have an "uh oh" moment.

• combustion by-products - the decrease in pH suggesting acid formation in older samples suggests micro-dieseling may be going on. Since the differential gear is partially immersed in the oil pool, I suspect that is the primary source. Many combustion by-products have conductive properties. This can result in a 'paraffin' odor.

In contrast to our transaxles, transformers are bathed in oil that is not exposed to mechanical wear by-products. As a heat transfer and insulation medium, the primary design issue is the absence of contaminants. I suspect the first Prius, the NHW10, may have had a special design feature that was dropped in the NHW11 and subsequent models.

The NHW10 Prius has seals that kept the transmission oil away from the motors. This would be a conservative, engineering approach if one did not know how worn transaxle oil would behave in an environment of 300+ VAC. The later versions used an improved 'plastic filler' to seal the windings.

Internally the stator coils are cooled in part by 'sling oil' from the rotors. This means the oil is flung against the inner surfaces. Some of the photos I've seen suggest a 'polishing' but without detailed, microscopic examination, I can't say for sure.

BTW, the plastic that encapsulates the windings has chemical-mechanical properties. I would always wonder about additives or even the molecular weight of the oil that might cause the encapsulation plastic to swell and flake off. But these are speculations best addressed by testing. Still, I noticed some tiny, shiny, clear pieces after the Amsoil ATF test that suggested clear plastic flakes.

Bob Wilson

[dogfriend]

Originally Posted by edthefox5

Hi,
There are no dielectric properties to the WS ATF.Please stop perpetuating this Internet myth.

I didn't realize I was somehow perpetuating an "Internet myth". All materials that are insulators have dielectric properties. Seriously. Its an inherent property of the material.

Do you have a statement from Toyota that states that the dielectric properties of the WS fluid are not important? Please post it.

All that I have is the statement in the owner's manual that specifies WS ATF for the NHW20 transaxle.

Fluid type:
“Toyota Genuine ATF WS” or
equivalent


They don't specify what the equivalent is, but if Redline D6 is certified to meet the WS spec then that probably qualifies as equivalent.

Like I said before, I will be interested to see the results of your UOA. I have nothing against Redline products and I think its great that you have volunteered to be the guinea pig on this.

Personally, I don't think its worth the risk, but that's just my opinion.

I will edit my post to acknowledge your objection.

[patsparks]

All I know is the only place I can find WS oil is a Toyota dealer. If there is nothing special about the oil why didn't they just specify Dextron III?

[edthefox5]

Originally Posted by apriusfan

I wasn't aware of dielectric properties of the WS oil. However, I don't think I would go to the extreme of using some other oil as a cost-saving measure (penny-wise, pound-foolish). I am not a lubrication engineer, but if the WS oil could be swapped for another oil, the aftermarket companies (redline, amsoil, and, and, and) would be all over the opportunity.

Hi,
Your not aware of it's dielectric properties because WS has none. And of course the WS can be swapped with other better fluids. Nothing special here its a Dexron VI. Amsoil makes an excellent product & so does Redline both GL-4 full synthetics. I am running Redline D6 in my 07 right now.And its sure not cost saving as a quart of Redline is $ 10. Worth every penny in my opinion. Here's some reading for you:


http://www.redlineoil.com/pdf/3.pdf

[edthefox5]

Originally Posted by dogfriend

I didn't realize I was somehow perpetuating an "Internet myth". All materials that are insulators have dielectric properties. Seriously. Its an inherent property of the material.

Do you have a statement from Toyota that states that the dielectric properties of the WS fluid are not important? Please post it.

All that I have is the statement in the owner's manual that specifies WS ATF for the NHW20 transaxle.

Fluid type:
“Toyota Genuine ATF WS” or
equivalent


They don't specify what the equivalent is, but if Redline D6 is certified to meet the WS spec then that probably qualifies as equivalent.

Like I said before, I will be interested to see the results of your UOA. I have nothing against Redline products and I think its great that you have volunteered to be the guinea pig on this.

Personally, I don't think its worth the risk, but that's just my opinion.

I will edit my post to acknowledge your objection.

Hi,
OK...how is Dexron VI an electric insulator? Thats all WS is. Its just Dex VI GL-4 auto trans fluid. Any GL-4 trans fluid made will run in our trans. But for proper viscosity & shear you must at least be at DEX VI for proper gear wear. And after a few thousand miles it becomes a very poor dielectric as it accumulates metals. AT 50,000 miles of use that's a pretty metal heavy fluid.
But what am I insulating from? What are you so concerned with that I don't conduct electricity across the fluid? Your argument is that the WS fluid will somewhere in its life be exposed to voltage leaking from the MG's and given that Toy has added some space age dielectric ingredient to the WS fluid so now it can't conduct electricity so I'm OK. I'm leaking voltage from a compromised motor field wire on a MG(which is how the few that have failed did fail) a crack in the conformal coating has exposed conductive portion of the wire and 500 volts is exposed to the fluid...but I'm cool cause I got special fluids in there. The inverter is stupid. It doesn't measure voltage level...impedance...capacitance....phase...load. It just doesn't care I'm leaking voltage into the fluid. No blown fuses no crow bar of the inverter. Its just a dumb brute force power supply.I'm rolling down the road happy with sparks in the trans.
I'm busting your chops here but I'm just saying there's forces at work here that makes your special fluid in consequential.
I guarantee you if even a tiny portion of the conductive part of the MG winding is exposed you will have quite a problem even if there's space age WS fluid in the trans. The WS will not fix that problem. You have 500 volts there and maybe 100 amps of power. That kind of voltage would quickly flash over to any surrounding metal area which given how the MG is built the wiring is laying on the metal case. What type of fluid ya got in there will quickly become the least of your problems whether it has insulating properties or not.
Which is why Toyota did not put special fluid in there. Why bother. If they had made special fluid I'm sure the dealer would love to make you bring your car in every 25K miles and kill you with it. Because you have to change the special fluid. Oh and the special fluid is $20 a quart. The dealer would love it. Instead the dealer touts 100k refill. I think there's many peeps here that can tell you what 100K WS looks like. Black with metal. Not alot of dielectric properties there. And the car will still motor on down the road.For another 50,000 miles or much more. You'll have gear wear of course but your dieletric argument goes out the window with the bathwater.
I'm getting ready to take my 6K WS sample pull to the UOA place in Tampa. I'll inquire if there's a test for dielectric properties. But I never heard of it. At least not for auto products.

[dogfriend]

I bought WS ATF for $5.20/qt at a local dealer parts dept.