I had my transaxle oil changed at 5,000 miles and the viscosity tested 5% down. The rule of thumb is a 15% decrease in viscosity indicates the oil needs to be replaced. Straight line, this suggests the first change should happen at 15,000 miles. Our ZVW30 is at 12,000 miles and I plan to change and test it again at 20,000 miles but that is probably eight months away, sometime around March 2011. However, some of you may have 15,000 or more miles and an interest in keeping the transaxle oil in a pristine condition. There are several oil testing labs but this is the one I use: R&G Laboratories, Inc or PdMA Corporation - Oil Analysis - Excellence in Lubricant Analysis My sample bottles are dry, former water bottles and only a cup is needed. Ask for their standard oil test plus 40C and 100C viscosity. It is the decrease in viscosity that lets us know the state of the oil. GOOD LUCK! Bob Wilson
For those of you who are not familiar with the history on the subject of refreshing Prius ATF, Bob has led a long term study along with a technically oriented group of Prius owners. The results of testing ATF first from 2001-2003 Prii and then from a few 2004-2009 Prii was that the ATF should be refreshed at reasonable intervals to protect the the Motor Generator windings and Torque Splitting planetary gears of our transaxels. One common result across the models was that there is an early build up of metallic particle load in the ATF as the planetary gears "lap" together during a break-in period. There is also a high silicate load in the factory fill that appears to be from dissolved materials from sealants used in the assembly process. The group's consensus to date is: 2001-2003: Do a first refresh of the Type IV ATF at 15k miles and consider switching to the newer Type WS ATF for further refreshes at 30k mile intervals. 2004-2009: Do the first refresh at 30k miles and then further refreshes at 60k mile intervals. My 2004 is coming up on 180k miles and it has had refreshes at 60k and 120k miles with the first having a much higher metallic load than the second. 2010-??: Bob's first report on the current model is above. If I had a new Prius, I would follow the 2004-2009 suggestions for now but an earlier first refresh can't hurt and I would follow Bob's reports closely as time goes on. JeffD
There is a notice on The R&G web site that says "not for individual or personal use". I took that to mean they only do business with companies, govt organizations, etc. not Joe the backyard mechanic? I ordered some sample kits from Blackstone Labs is there any problem with them? I have a transaxle sample from 20K miles in my garage I will send in. Also going to have motor oil tested after 10K summer miles on Mobil1 0W20.
I was thinking about Bob's transaxle oil viscosity tests the other day when my GIII reached 18K. Any suggestions on replacement oil? Synthetic?
The Toyota type WS is a proven, good product. Why risk possible problems experimenting with others. Bob tried Amsoil ATF in his older Prius and found problems with it leaching copper from the transaxle. Others have been experimenting with Redline. I would let them do the experiment and see if there are long term problems. I have been using R&G with no problems. I'm sure that Blackstone does a good job as well, but it is difficult to compare results between different labs as their processes differ. JeffD
I think it's one of those cases where it is far better to use the Toyota product, ATF type WS. If there were not anything in the transaxle case but some gears we could probably use other types of gear lube but there are high voltage components, MG1 & 2, etc, and we don't know what effect other gear lubes or ATF fluids would have. You need 5 quarts of ATF-WS, $7.78 per quart at the local dealer.
Makes sense to me, especially about the high voltage components, Motor generators. That's a twist you normally don't run into when your talking transaxle oil. Thanks Tom and Jeff! George
There are several but the only problem I had with Blackstone is they used to do only one viscosity temperature test. The 40C/100C test lets them calculate something called the oil viscosity index, which as a single number, gives a good idea of the oil wear. However, things change and I don't see anything else either for or against Blackstone. There is another one in Texas: http://www.dysonanalysis.com/ They seem to do a reasonable job. The problem with different labs is the possibility of slightly different calibrations. I know the labs work hard to be uniform but it is much easier to deal with if within the same lab. But I'm not hard on one or another lab. If you're happy with Blackstone, keep using them so you'll have continuity of tests. I started with PdMA who then spun off R&G. I have 5 years of history with them so I'm loath to change unless there is some compelling reason. Bob Wilson
From memory: dealer - it was at the 5,000 mile service call ~$65 - what I remember from the bill $20 - oil test with 40C/100C viscosity test $45 - particle test (microscopic examination of oil) The particle test is not necessary but satisfied my curiosity. Bob Wilson
