2004 Transaxle Oil Analysis

Recently I was sent the oil analysis of a 2004 Prius with 110,000 service miles upon its first change. Fortunately, Jeffrey Denenbery shared an even more interesting set of data. First the data:

	Column 1	Column 2	Column 3	Column 4	Column 5
0	PdMA @120k total	60k service	PdMA @61k	PdMA ref	element
1	97	206	1	Fe
2	20	21	0	Cu
3	1	3	0	Sn
4	1	1	0	Pb
5	1	2	0	Cr
6	3	7	0	Ni
7	53	56	1	Al
8	106	115	109	Ca (additive)
9	2	5	0	Mn
10	6	8	0	Zn
11	264	227	245	P
12	3	20	0	Ba
13	64	153	2	Si
14	0	0	0	Na
15	59	27	59	B
16	22.3	21.3	24.6	cTs @40C
17	4.9	4.7	5.5	cTs @100C
18	150	144	171	Viscosity Index

* PdMA is now known as R&G Labs. PdMA results.

OPINION

Obviously the first oil change has significantly improved the outcome of the second 60k miles. Every wear material metric is improved. Best of all, there is no sodium, the signature of a coolant leak.

"Machinery Lubrication" has many articles about the risks of water getting into a lubricated system. Coolants carry a detectable amount of sodium and as long as the transaxle oil test remains free, it will remain in good shape.

One other aspect of water in lubricants is the loss of dielectric strength. There have been a number of NHW11 transaxle failures that involved internal shorts that failed MG2 stator. Sad to say, we've never gotten an oil sample to test. For more details, I would recommend using the search function at:

Machinery Lubrication Magazine Home (1.)
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I would like to thank all who have sent oil samples for analysis. But I can not afford sample testing ... now that we have a pool of knowledge. I don't mind sharing what little I've learned but at $20+shipping, it gets a little pricy to also pay the testing fee.

I can not over emphasize the importance of getting an early, transaxle oil change. My 5k change of our 2010 Prius (ZVW30) came back with a high Si and Fe levels. The straight-line viscosity loss suggests a 15k life of the original oil. I suspect we will find the Type WS has a similar if not slightly higher than 60k service interval after the first change.

Bob Wilson

1. Oil and Glycol Don't Mix

 

Hi Folks,

My apologies for the major rewrite of the original posting. As is my practice and a common courtesy, I sent an e-mail link of the original post to both the original user and their lab. That way if I've gotten something wrong, we can easily correct it. But the follow-up e-mails made it clear my understanding of 'fair use' and intellectual property rights may not match one party's understanding. I'm here for the Prius technology, not splitting legal hares (I meant 'hares' as I'm running away from such folks.) Fortunately, there are other sources who share our technical interest.

All possibly, remotely, copyrighted material has been edited out of my first posting and none of the follow-up postings are at risk. I am securely deleting the original e-mail and data from my personal computer.

Bob Wilson

 

So far, I've looked at several alternatives, Redline(?) Blue Velvet(?), but each one had higher, 40C viscosity than the Type WS. The only oils I've found that even come close are some aircraft turbine oils ... it is that good. There may be a better oil out there but so far, I've not seen it in the oil specifications.

My one test with Amsoil AFT for Type T-IV, NHW11 2001-03 Prius, was not a good experience as the copper rates went too high for my tastes. I suspect there is a materials issue and there was one report that Amsoil is not good for 'yellow metal.' My oil testing supports this claim.

Oil suppliers provide different additives to reduce foaming, expand the viscosity range, reduce friction and improve the oil quality. However, a good design team that knows the materials in the transaxle knows to avoid some additives. For example, molybdenum is found in engine oils but not a trace in the Type WS or Type T-IV oils. I suspect it is hostile to some of the materials in our transaxles ... possibly forming a conductive surface or interacting with magnets. Regardless, I can not recommend any transmission oil that uses it.

Bob Wilson

 

I found it: AMSOIL - Synthetic Fuel Efficient Automatic Transmission Fluid (ATL)

The 40C/100C viscosity is more than I want for Type WS but it may work with our older, NHW11 transaxles:

	Column 1	Column 2	Column 3
0	40C cTs	100C cTs	Transaxle oil
1	35.3	7.4	Type T-IV
2	29.8	6.0	Amsoil efficient ATF (*)
3	24.6	5.5	Type WS

* - includes a copper corrosion metric

I'm still running Type WS in my NHW11 and that experiment has at least one more year.

You've got your priorities right. I wish I could help but Huntsville AL is a bit of a stretch.

Bob Wilson