This is why Redline D6 is not the best ATF in Prius

How do you know its 250ppm? Once I asked Dave if he had a UOA for the virgin D6 & D4 and he did not. I was surprised and bummed.
Either way I will move over to D4 next time. I'm due. Thanks.

 

Just to drag it up again,,,

I do know what gliderman was getting at above....

It's just a gear box. Does it require 'extreme pressure' properties in the lubricant?
There aren't any hypoid gears, right?
Where are the high pressure contact points? The spider gears in the differential? The many little planet gears?
If EP is not required, why not a light MTF or even a light engine oil?

Honda spec'd 10-30w engine oil in their manual transmissions for decades (?).

The Prius gearbox is way closer to a manual than an automatic transmission.

I need to get the extreme wear that I saw in my gearbox stabilized first.
( First fluid change at 112k miles. ) [ Thanks Toyota ]
After a change or two with good analysis results maybe a little real experimenting with lubricants may be in order !

I was looking at aircraft jet engine oils like BP 2380, Mobil Jet Oil II and 254.
But there is a Caution on the cans: "Avoid spilling on insulation, plastic, rubber or paint".
Turbo Props have planetary gear boxes. And all jet engines have 'rubber' oil seals. But finding the composition of the seals and what Toyota uses is too much work...
Plus the stuff runs ~$18 a quart.

This promises to be an informative thread. Thanks!

 

So am I which is why before I did my first transaxle oil change, I used a stretch of cold weather to measure roll-down performance before and after the change. Later, I found Amsoil was associated with higher 'yellow metal' loss and I could see it in my oil tests. But I had learned enough about Type WS viscosity to switch from Type T-IV to Type WS and feel confident this oil would have the minimum viscosity losses and thus coolest temperatures. BTW, changing to Type WS is cited in the Toyota SAE paper as one enhancement to the NHW20 Prius drag reduction.

What I don't have are hard metrics to quantify the change. But as long as my oil analysis keep coming back good, I'm sticking with what works.

GOOD LUCK!
Bob Wilson

 

I thought Gen II needed better trans OCI's until I saw these posts with pictures for the Gen III. Wow they look bad. Not sure where the milkyness shown on F8L's is coming from but very disturbing.
Like changing out an old differential. Milkshake. Bad.

 

Fun, but expensive experimentation. In my opinion, it is better to use what is recommended by the guys who designed it, among them people who did nothing else but consider this question for their living. The data are interesting though.

 

Conventional automatics have multiple friction clutches that wear and must have smooth, chatter-free
slip-to-engagement. This may be why there are so many and varied 'friction modifiers' in the various recipes of ATF.
And this is why OEM recommended additives like Lube Guard will get rid of clutch chatter after adding the little 4oz. bottle. I did this with a Subaru SVX and the center diff clutch was chatter free in 10 mins.

The Prius never 'shifts gears'. They are always engaged.
The most you see is a phase change on 2 of the 3 phases powering the MG's.
I've been 'shifting' between R and D and back again at slow rolling speeds and even that is so smooth.

Bob, there are some questions about your coast down test done on that Gen1 long ago. You just say 'warm'. Wouldn't an overnight cold soak, outside , same outside temp, same wind/pressure altitude, same short drive (push the car?) to the top of the hill, be a better test? Soap Box Derby !!!!
Can a few Vis points really be seen with this sort of test?

And " higher yellow metal loss" ,,, how is that quantified? Could it be there is a bronze bush, (or many), in the Gen1 gearbox?
The test I can find that is used by manufacturers is:
The Copper Strip Corrosion Test ASTM D130 is used to evaluate the corrosive tendencies of oils to copper containing materials.

Read more: http://priuschat.com/threads/atf-fluid-changes-are-required.119530/page-4#ixzz2IQmhYBUm

Are you saying there is some aspect of Amsoil that is just plain dissolving copper wires?

Just some tech-nerd observations, Thanks,,

 

Bubba,

Not too expensive to do this. $40-45 for a gallon of fluid and some on your back time.

Oh, and $15 for a postage paid oil analysis kit.
Please guys......

And these guys: the guys who designed it, among them people who did nothing else but consider this question for their living.

What were these guys 'considering' when they said:
"Just leave that fluid in there forever. You should be just fine." (in Japanese) ?

 

The cold temperature, roll-down tests were conducted with an overnight, cold soak and the car parked so I could pull straight out. The steepest downgrade of the hill is 50 yards from the house so I would reach the same, neighbor's drive way each time, stop and turn off the engine and then back to IGN. After one last check to make sure there was no traffic and record the car reported, outside temperature, I put the car in "N" and released the brake. The car would roll down the hill and at the bottom, it flattened out. I would mark on the map where the car stopped. Tire pressures were kept normalized at 51 psi.

Not only the bronze bushing that was replaced by a bearing in the NHW20 but both cars have a 'silent chain'. Although I have not taken one apart, I suspect the links have bronze bearings. But I was initially clued about an internet posting warning about a yellow metal problem.

I was initially impressed with the improved Amsoil performance in the roll-down tests. But I could tell there was oil carry-forward. When I did the 7,000 mile change more as a flush of the residual oil, I found:

• 75 ppm, 53,000 mi., Type T-IV original oil -> 1.41 ppm/1k miles
• 28 ppm, 7,000 mi., Amsoil ATF -> 4.0 ppm/1k miles

The report was 'yellow metal' suggesting bronze is at risk. The high rate of copper found in the 7,000 mile Amsoil sample was enough that I didn't want to continue the experiment. I just did a Google search and found references to sulfur being a problem with bronze but my oil analysis did not include a sulfur metric. I don't know the exact mechanism but the oil analysis pretty well showed there was a problem so I switched to Type WS.

Bob Wilson

 

Yes and you can find them in the files section of the Yahoo Group, "toyota-prius-sat2", a satellite group to "Prius_Technical_Stuff." You'll need to join the groups and I would recommend:

• Prius_Technical_Stuff
• toyota-prius-sat1
• toyota-prius-sat2

Once you get access, feel free to post questions either in "Prius_Technical_Stuff" or here and I'll be happy to share anything I might have forgotten. Oh, the message search function works well too.

Bob Wilson

 

Interesting.

Thanks for the info and the reasoning behind it. FWIW, Redline's application page recommends D6 for Gen III Prius, but the D6 spec sheet doesn't list it as a WS substitute. Looks like their website needs some housecleaning

 

Old dog, new tricks:

This is impressive:
Red Line Synthetic Oil - Automatic Transmission Fluids - Lightweight Racing ATF

• 4.9 @100C
• 23.2 @40C
• $50/gal + $13/quart

Sad to say, I've got two transaxles worth of Type WS waiting on a nice day to change and send out samples.

Bob Wilson

 

From their web site description:

* * * quoted * * *

• Superior consistency and wear protection for Bracket and Heads-Up drag racing transmissions like Powerglide and Turbo 400
• Popular with turbo and blown doorslammers like NMRA, NMCA, ORSCA, and PSCA -- replaces hydraulic oils and other non-ATFs used to escape heat issues
• Low viscosity offers less frictional drag for quicker ETs and more MPH
• Dissipates heat for longer trans life, better clutch, gear, and seal life
• Compatible with petroleum ATFs and other brands synthetic ATF
• Extreme-pressure protection provides much better film-strength

• Red Line offers the widest selection of fully-synthetic ATF on the market today
• Each offer improved thermal stability, maintain viscosity levels, and feature lower volatility while providing the required frictional characteristics of each fluid's OEM-style replacement
• Reduced oxidation and lower volatility at high temperature
• Allows high-temp operation without varnishing valves and clutches
• Extended drain intervals

* * * end quoted * * *

I am after low viscosity and film-strength. But it isn't clear what metrics are involved in "friction modifying properties."

Where in the Prius transaxle are 'friction modifying properties' important? I could see them having use in heavily-loaded, bushings but I am not aware of any 'stressed' bushings in the current transaxle. Perhaps the differential gear but it seldom has much rotation except in turns and even then, very limited operation. I am pretty sure even the drive shaft axles are bearing supported. The NHW11 and NHW20 still have the silent chains so there it might be important.

Regardless, the first step is to get a virgin sample and send it to the lab for testing.

Bob Wilson

 

You should have seen the posts I got when I switched to Type WS in our 2003 Prius . . . nearly seven years ago. It is a serious question because I've self-studied lubrication including subscribed to "Machinery Lubrication" for as many years and augmented it by having mine and other oil samples tested. Heck, I've even done (and consider it a primary metric) roll-down tests in freezing weather. My understanding are friction additives are a class of dry lubricants.

Near as I can tell, dry lubricants, are best used are in bushings with high loads and stop-start operation . . . places where film lubrication is difficult to achieve. The silent chain in the NHW11/NHW20 would be an example and the NHW11 has one gear on a bushing. But I'm more interested in a stronger and better film strength as we slowly get the early crud out of our transaxles.

BTW, I tried boron nitride (Motorsilk) in our 2003 engine. The physics looked right and I tried to measure the effects. But I could find no empirical in the OBD data. It doesn't mean there were effects but they were too small for me to detect.

Bob Wilson