Transaxle Oil Analysis

My recently purchased 2008 Prius had a little over 60,000 miles on it. I presume the Transaxle oil had never been changed. It had some red tint to it but mostly it was a dark blackish red. Here is the result of my Blackstone oil report.

 

Here's the results from a recent change on my 2007 Prius. I originally changed the fluid at 30K (but didn't do an analysis). This is from the 80K change.

 

So according to old owner the transmission fluid on my car was changed at 164k miles at the Toyota dealership.

At 235 k (Oct 2011) I decided to change the fluid. So I bought a pump, washers and 4 quarts of Toyota ATF WS (whatever it is called).

As soon as I opened the fill valve (top valve) a little drop of transmission fluid came out and dropped on my rubber mat. I was red in color (as I can remember) and I checked its consistency and it was quite rubbery and didn't smell of carbon or sulphur etc.

It looked as good as new to me and so I decided not to change the fluid and returned all the stuff back to Toyota and AutoZone.

I am a 241 k miles now.
Should I be worrying about the transmission fluid?
Is a non-lab test (what I did) fine?

Since I have seen plenty of people reporting to see black color fluid etc (which I didn't see) I hope you can shed some light on this.

 

Excess casting metal will be in the first flush, subsequent flushes will only have wear metals, wear minimizes over time.

Could you go 90,000 between changes at your mileage, could be.

At risk is a minimum $2000 used transaxle replacement, I would have spent the money on new fluid, You should by 30,000 from now.

 

Well, do I understand correctly that you're all recommending transaxle oil changes at 60-100k miles, even though transaxle oil change does NOT appear on Toyota's maintenance schedule?

My 2010 just got its 105,000 mile service with one mechanical issue - the hood latch release was out of adjustment and I couldn't open the hood. Car is otherwise mechanically perfect. I feel really, really fortunate.

 

I changed mine at the one year anniversary, think it was around 15000 km. I'll likely continue to do changes every other year, so around 30000 km interval. It's fairly simple, costs about $40 in materials, was an easy decision

 

Changed my 2006 Prius transaxle oil this weekend at 104,000 miles. Oil was black. Hard to believe it started off red. That is an easy change -- as easy as an engine oil change in my opinion.

My dealer wanted $199. I asked several times. Crazy!!

 

Note: originally posted in another thread, I just noticed someone asked me to post it in this thread also.

I had the transaxle fluid replaced 6/10/2010 (at 70,598 miles) at a local dealership for $79.66 all-up. The service writer didn't appear to know much about the Prius, but I'm getting used to that. They took a 1-pint sample for me which looks and smells good, but I'm going to run it through some filter paper and see if there's any particulates in it. They didn't comment on the drain plug appearance, or when in the drain process they took the sample. I'm sending a sample off to PdMA (now R&G (I think) Labs, 813-643-3513).

Update: Their summary: The iron, aluminum, and copper content have been flagged for observation. Abrasive contamination is suspected based on the silicon content. The sample from this unit contained trace water contamination.

Details:

WEAR METALS
Iron Fe ppm 175
Chromium Cr ppm 3
Molybdenum Mo ppm 0
Aluminum Al ppm 54
Copper Cu ppm 26
Lead Pb ppm 2
Tin Sn ppm 3
Silver Ag ppm 0
Nickel Ni ppm 8
Vanadium V ppm 0
Titanium Ti ppm 0
Manganese Mn ppm 5
Cadmium Cd ppm 0
CONTAMINANT METALS
Silicon Si ppm 195
Sodium Na ppm 7
Boron B ppm 35
ADDITIVE METALS
Magnesium Mg ppm 3
Calcium Ca ppm 103
Barium Ba ppm 19
Phosphorus P ppm 221
Zinc Zn ppm 37
NON-METALLIC CONT.
Water % vol Trace
Solids % vol <0.1
LUBE DATA
Viscosity @ 40'C cSt 21.7
Viscosity @ 100'C cSt 4.7
ADDITIONAL TESTS
Viscosity Index 139
Severity:
Recommended Action:
(MH) - Moderately High

 

I bought the car new and changed transaxle fluid at 5K miles. Used fluid analysis from the same lab (R&G) flagged Si at 135 ppm as suspected abrasive contamination. I would think it's more likely the result of leaching of new sealants.

 

I'm as little worried about the people that tell you how your oil is, saying "as long as it's shifting well".

 

Well I finally changed mine, hate that I waited soo long. Also changed over to Mobile 1 Synthetic Oil this weekend. I have 144k on my Gen II with a flawless service record, I have also been very great full of my wonderful vehicle. I wish I would had looked at these sites earlier as the plug magnet was full of shavings and metal particles. When I poured the fluid back into the containers the new fluid came from, there was a mesh grill on my funnel, and even more particles were captured. See the pictures below. Oil was also pushing much longer than I usually do, I usually have it changed at Firestone every 5500 miles, along with tire rotation and alignment.

Thoughts, would it be worth anything to send this ATF off to have it analyzed?

Strange observations, the 2 ATF's on the paper towel look very different, but after 5 min, you would barely tell which one was the new and old. When the fluid was in the yellow pan, it almost looked like engine oil.

 

What I found was the first, 5k mile change, showed evidence of early wear and possibly left over debris from manufacturing. My thinking is:

• early change, 5k miles - this initial flush removes the early wear material and sealant silicon. The viscosity change suggests a 15k mile service life.
• second change 15k miles - this removes most of the residual oil not removed in the first change and addresses any viscosity change.
• subsequent 60-90k miles - now we're dealing with sealant leaching and viscosity changes

Now in ordinary service, I believe the surface bearing wear shows up as microscopic particles, more like a suspended smoke. It does collect on magnets and looks like a very dark, goop. The problem is this stuff is large enough to penetrate the lubricating, oil film. Subsequent removal should reduce drag but also the future wear rate. So early changes lead to getting the stuff out so later changes can go longer intervals.

Bob Wilson

 

Transaxle fluid analysis 5K vs. 25K miles



Analysis done by R&G Labs. Factory fluid changed at 5275 miles. Recently the 2nd fluid change was at 31336 miles. Wear metals looked fine. Reduced Si level is consistent with the idea that the source of Si is the sealant, not contamination. Viscosity barely moved from 5K to 25K miles of oil life. It won't need oil change until another 60K miles I think.

 

MPG before vs. after transaxle fluid change

It's a frequently discussed topic: whether the transaxle fluid change affects fuel economy. The best argument I heard was from Patrick Wong that, if anything, one should get slightly lower MPG after the change due to the higher viscosity of the fresh fluid. Here I plotted MPG vs. outside air T for a dozen or so trips before and after the recent fluid change:



Other than the two outliers due to rain and A/C use, we see that indeed the fluid change does not affect MPG much at all. There is a small trend of lower MPG after the change but it may just be noise. The trips are on my regular familiar commute routes with usual traffic conditions and same driving habits.

 

I was able to measure lower rollong resistance during freezing weather, roll dowwn tests. But the effect disappeared at 40F/3-4C. These are the worst, hiighest viscosity temperature curve areas. However, my original oil also had a substantial particle load.

What we find is over time, the oil viscosity "shears down." The good news is this leads to lower viscosity friction but it also means thinner oil film and risks more wear products.

Bob Wilson

 

I have a 2007 with 84,300 miles. Purchased used a year or so ago with 75,000 miles. I changed the transaxle oil with reference to these posts. Cost in Memphis area is now $8.00/qt. Blackstone report shows lots of metal but probably due to long chg interval and wear-in. They suggest another chg in 80,000 miles. Mileage went up from 46mpg to 54-55 range, but the recent trips we have been making are in the 45 mph conditions.

Aluminum - 144 avg 46
Iron - - 321 avg 121
Silicon - - 201 avg 120
SUS visc @ 210F -41.4 should be 43-52
cst visc@ 100 C -4.59 should be 5.1-8.2

Sidenote..... 09 Camry had a very slight coolant leak. If this goes unchecked past the 5yr drive train warranty you pay for the repair. Some have speculated that casting material is the culprit. The 5yr coolant life lets the material work on the water pump seal. Make sure you check under that hood every now and then.

 

I first changed my transaxle fluid at around 125k, then again recently at around 225k - analysis of that change is attached.

 

Thank you all for posting the UOA results.

I went ahead and calculated transaxle wear rates expressed in ppm of Fe per 1000 miles for gen 2 for factory fill ATF. They range from 2.5 to 11 ppm Fe/1000 miles. Shorter interval results in higher numbers due to accelerated break-in wear. No big surprises, but I PMed some of you if your numbers were better or worse than expected. Thanks for getting back to me and I will provide a feedback if I get more responses.
Please see the attached chart. Y-axis is Fe ppm/1000 miles, X-axis is 1000s of miles.

 

Hi everyone, I am unable to find the lipstick anywhere in the engine to check the status of transaxle oil? It's a fluid I guess which is required by automatic transmission gear. Pls correct me if I am wrong and if that is the case then where is the opening slot thru which said oil / fluid is changed with new one, when its needed.
Thx for ur responses.
Rgds,

 

Sajjad,

There is no dipstick to check. Please see the discussions above on how to change the fluid. You should be comfortable working underneath the car and working with cars in general before doing this. It's not hard, but there are things that can go wrong.

Good luck!