[attachmentid=9778]I did a used oil analysis (UOA) on the CVT fluid. I have read that some have determined that a change at 50000 miles on the transmission fluid is a good idea. Based on this data from Dyson Analysis an even shorter interval is a good idea in my opinion, even though the recommended interval is "lifetime". I will also attach it in an excel file for readability. Dyson Analysis 6/30/2007 2004 Prius CVT Fluid Toyota WS Trans Fluid Oil Miles ___ 65553 Trans Mi___ 65553 Iron______ 318 Copper____ 25 Tin_______ 0 Lead______ 0 Chrom____ 4 Nickel_____ 10 Alum_____ 77 Titan______ 0 Silver_____ 0 Calcium___ 134 Magnes___ 5 Zinc______ 15 Phosp_____ 210 Barium____ 24 Molyb_____ 0 Antim_____ 0 Silicon____ 179 Sodium___ 5 Boron_____ 58 Potass____ 0 Vanadium_ 0 Visc40C___ 21.1 Visc100C__ 4.8 TAN______ 0.85 Flash_____ 325 Oxida_____ 43 Nitrat_____ 5 H20(KFppm) 311 TBN______ 10.2 Fuel______ NT Soot______ 0 Visc Index_ 155 Sulfate____ 33
<div class='quotetop'>QUOTE(maineprius947 @ Jul 16 2007, 09:09 AM) [snapback]479541[/snapback]</div> Attached is a pdf of the analysis done by PdMA on my 2004 Prius ATF at 61,000 and of virgin Type WS ATF for comparison. Results are similar, but you had higher amounts of wear metals. I will do it again at 120,000 miles (at 90,500 now). JeffD
Gimme some idea what the normal/acceptible range is for those various components in this type of fluid please. Hard to know what those numbers mean.
<div class='quotetop'>QUOTE(efusco @ Jul 16 2007, 10:05 AM) [snapback]479558[/snapback]</div> The levels that are of particular concern are Fe, Al, and Si. Often Si is from dirt, but it can also be from seals and such leaching Si into the fluid. Typically a good analysis would have Fe and Al levels about 1/5 to 1/3 of the levels in my report. Dyson Analysis tends to get higher wear numbers than many other labs and supposedly uses more sophisticated techniques so it is difficult to make comparisons from one lab to another. For reference, an engine oil sample at 5000 miles typically has Fe=5 ppm and Al=3 ppm, if you multiply by 13 to get 65000 miles you would have Fe= 65 ppm and Al = 39 ppm. I don't have access to "normal" values for a Prius, but the fluid change is something a decent mechanic could do in 15 min and the fluid costs about $40 so it could be done for $75 at an independent shop if you bring 4 qts of fluid from the Toyota dealer. Not a bad preventive maintenance item if you plan on keeping the car. I think jayman has mentioned that an early change of the Transmission fluid at maybe 10k and then shorter changes of maybe 30k would be prudent. Based on my uoa and the other analysis above I would agree. I plan to take a sample at 15k on the current change and get it analyzed and will post those results (probably next spring because I only drive about 20k per year). Note that many of those components are additives and a TAN of less than 1.0 is good, but the wear metals (Fe, Al, Cr, Ni, Sn) are the main thing to pay attention to as well as the viscosity. If you compare the viscosity of the virgin fluid to the fluid with 61k on it you will see that it thinned a little, but not excessively in my opinion.
I plan on doing a CVT fluid replacement (and sending the fluid off for analysis) at 5,000 miles, so there will be another set of data for consideration of metal/contaminant levels. Wonder if this thread should be turned into a sticky? Which lab was used? I was planning on using Blackstone, but for consistency, it might be better to use the lab the OP used.
I've been using PdMA: http://hiwaay.net/~bzwilson/prius/pri_T_cold.html#TRANSAXLE My interest has been in Type T, the NHW11 OEM oil. However, more and more of us are switching to Type WS because of the improved viscosity. PdMA points out that a 15% loss in viscosity is their threshold for end of life. Also, the Si/Al rates are a primary indication of contamination. So far, the collected data suggests Prius from dusty areas have a greater problem than those from less dusty areas. In the meanwhile, I'm testing a homegrown solution, a transaxle vent plug to avoid the negative pressure in the transaxle. If you're interested, my results can be found here: http://hiwaay.net/~bzwilson/prius/pri_toil.html http://hiwaay.net/~bzwilson/prius/pri_T_cold.html http://hiwaay.net/~bzwilson/prius/pri_tt.html BTW, I am interested in any transaxle oil test results to add to the database. Bob Wilson
