ATF fluid changes ARE Required.

With respects, but what you do what for a living? Your opinion to "obsessive over maintenance" is what keeps planes flying, the trains rolling, ships shipping, industry running and the military protecting. The lack of is also what keeps the average person (not all) buying a new car every few years. Do you know how many homes could have been paid off were it not for the continual car payment program so many are caught in and a part off? To repeat..."Take my advice..... or not....but I am qualified". My recommendation is based on decades of experience and knowledge obtained in my profession to it's current state. It is not the opinion of someone from another field, as I eluded to in the opening statement of my last post. I respectfully guaranty not to tell you your business if you a Doctor, or of any other profession for that matter, that I am not a part off.

You might want to reconsider your Brake fluid, Inverter and Engine Coolants as well, but lets leave that for another thread. Sorry for the digression. Ya'll have a wonderful evening.

 

I actually did that once, absent mindedly started pouring motor oil into an automatic transmission (not our current vehicle). I stopped after I'd put maybe a cup in, swore a bit, bought 3 times the usual capacity of the proper fluid, and did a triple drain fill, driving a bit after each.

But to purposely use an alternate fluid..., when Toyo's documentation says emphatically what to use...

My business is dimensional checking, in a consulting engineering firm, fwiw. I've said, just half in jest, that it can be worthwhile to check the obvious, like:

The top of a stair is higher than the bottom.

The area of a concrete pedestal is less than the footing it rests on.

Stuff like that.

To add to the list:

That the cheap fluid for the intermediate transaxle fluid change is actually cheaper than ATF-WS.

 

So I was stupid and over torqued the plugs doing the job this weekend. I went off memory and did 39 ft lbs instead of 29. 39 is N m in the book. I won't have a chance to really look at it until the weekend. I'm hoping the gasket bore the brunt of my mistake and I didn't damage threads. How freaked out should I be? I'm really kicking myself right now. Stupid mistake.

 

Should be fine, leave it alone if it doesn't leak

 

Just my suggestion... perhaps starting a new thread on the subject with less accusatory language. I don't think you will find many that disagree the fluid should be changed. The frequency is possibly another story. Based on the UOAs, people can make up their own minds.
Ultimately we don't have any solid proof that not doing it will cause premature failure. So you really can't say Toyota "dropped the ball". IMHO.

 

Bill, welcome to car forums.

Most (not all) of the members here are neither mechanically inclined or knowledgeable. Reality Check....we are talking about Prius owners. In fact, most people in general, know or do nothing more than gas up, drive and buy a new car every couple of years. You are more likely to be criticized for "wasting money" on maintenance, and complimented for "wasting more money" for body kits, stereos, lights and other aesthetics on this site. The people on this forum are actually a very good bunch when compared to most, but considering the perceived demographics, do not take it to heart if their priorities are not the same as yours. Just accept it and move on to the next topic. There is a lot of good stuff in here covering most subjects.

 

I have a perhaps silly question here: aren't there powerful magnets in MG1 and MG2 in the transaxle? If so, why are we seeing *any* metal at all in the UOAs? Also, should the magnetic drain plug suggested by the OP be more powerful than the magnets in MG1 and MG2 to be able to attract the metal that those magnets missed?

 

I suspect the metal people are seeing consists mostly of aluminum and brass. My 2nd UOA showed a high concentration of aluminum. I agree, the big magnets in the MGs will be more powerful than the magnet on any of the magnetic drain plugs, but I guess they can't hurt anything.

 

I dropped a neodymium HDD magnet in the used trans (27K miles) oil container and pulled tiny tiny metal dust on it after three days in the trans oil. I would stir the oil every evening with the magnet.

my2cents

 

"BTW, I was a 737-800 CAT III avionics guy for one of your competitors for a while. Love your cattle cars ! "

Don't you just love those new LED cabin lights. Hope you're happy were you are now. Think I'll take my own advise because now they are going to argue (magnetic) chip detectors.

 

Bill,
This is a great thread and your UOA results were very informative. This prompted me to change ATF in mine and do lot's of reading on a topic, in which I have great interest myself.

Why don't you look at the particle analysis posted by Bob on his NHW11 or NHW20 at 50-60,000 miles: 2003 Prius - Cold Weather and Transaxle

The results show lots of harmless small particles but rare particles at the size that is harmful, that is over 14 um. This is why normally there is no huge benefit to replace factory fluid; especially as a careless procedure can introduce outside hard abrasive particles that would be even more harmless compared to soft wear particles.

Now, if you compare to your wear particle analysis numbers after the ATF flush, you have lots of abnormal large particles. To me, an armchair tribologist, this looks like accelerated ABNORMAL wear and the fluid flush was a very good idea, but it may or may not stop the abnormal wear. Keep checking.

BTW, this is a reference to the particle size vs wear correlation (took me forever to find): http://cdn.intechopen.com/pdfs/31706/InTech-Effect_of_abrasive_size_on_wear.pdf

 

I took a fresh look at the oil analysis. The analysis report could have been a little better (*) but
there are some insights to share:

	Column 1	Column 2
0	[tr][th]wear[th]112	00 mi[th]420 mi[th]% decrease
1	[tr][td]Cu[td]43[td]5[td]11.6%
2	[tr][td]Fe[td]391[td]54[td]13.8%
3	[tr][td]Si[td]154[td]26[td]16.9%
4	[tr][td]Al[td]382[td]85[td]22.3%
5	[tr][td]total[td]970[td]170[td]17.5%

Source: first post

These are wear materials with statistically significant metrics at 420 miles. When values are too small, a single digit change makes too large of an impact, especially when used to calculate a percentage. What we see
is about a 17% carry forward of the original oil, the part that can not be drained without disassembly.

	Column 1	Column 2	Column 3
0	[tr][th]particles[th]size u[th]112k mi[th]420 mi[th]vol. 112k mi[th]vol. 420 mi.[th]% change
1	[tr][td]4u[td]4[td]70	318[td]50	908[td]18.9[td]13.6[td]72.4%
2	[tr][td]6u[td]6[td]48	550[td]6	029[td]43.9[td]5.5[td]12.4%
3	[tr][td]10u[td]10[td]13	413[td]101[td]56.2[td].4[td]00.8%
4	[tr][td]14u[td]14[td]1	770[td]77[td]20.3[td].9[td]04.4%
5	[tr][td]18u[td]18[td]293[td]63[td]7.2[td]1.5[td]21.5%
6	[tr][td]21u[td]21[td]133[td]56[td]5.2[td]2.2[td]42.1%
7	[tr][td]38u[td]38[td]13[td]29[td]3.[td]6.7[td]223.1%
8	[tr][td]50u[td]50[td]6[td]17[td]3.1[td]8.9[td]283.3%
9	[tr][td][td][td][td][td]157.8[td]39.7[td]25.2%

Source: first post

What is interesting is to see the smallest particles rapidly fall off and then the significant increase in large particles. This is a real head scratcher.

My speculation on the small particles is they may be replenished by the next larger size particles. This would deplete the larger ones but this speculation falls down at 18 microns. From 18 microns and higher, the total large particle size increases, significantly. Perhaps a detergent or dispersant raised them?

Having an an oil analysis is better than not. However, R&G Labs also provides 40c and 100C oil viscosity, a key metric for how well the oil is working. Also, they hold the sample for 30 days so if you see something 'strange', they can go back and do additional tests. For example, the larger chunks seen in the 420 mi sample, it would be great if there were a microscopic analysis to identify these particles.

Bob Wilson

 

Bill where is the TBN and TAN numbers on those reports?

 

You have to wonder why anyone would be SO determined not to use the correct ATF WS.