High Mileage trans fluid change

[Pilot2 0]

Just bought a 2007 is250 with 155k miles. Transmission shifts very smoothly. I do not know if the fluid was previously changed. Having heard stories of problems developing with trans fluid changes in high mileage cars, is it likely safe to change?

[dibley22 0]

I understand your concern for sure ..Ihad a similar issue re my 2007 lexus gx 470 with 81000 miles which I have owned since new..my dealer did not want to do the job as they appear to not recommend it..Iwanted to do it because after 12 years my gut told me that the fluid has to have degraded or gotten pretty dirty..I took it to a well recommended shop ..they ordered the toyota fluid and did the change ..cost me 225.00 ..mechanic let me see pan once it was off the truck and old fluid draining ..no bits of metal or whatever at bottom of pan which is magnetic..3000 miles later no issues or problems all seems ok....Before  having the change done I called that radio show "THE CAR PRO" he said very clearly ..change the fluid but"BUT DO NOT FLUSH IT "..so I pass this info on to you ..I hope it helps. Pete

that kind of made me feel pretty unsure as what to do.. 

[Pilot2 0]

is250-transmision.pdfI had Blackstone Labs perform an analysis on the 155,000 mile WS transmission oil in my "new" 2007 is250; the results are below.  In short, the Toyota WS fluid, even after 155,000 miles, was still performing its job.  The "universal averages" that Blackstone has for this transmission was with 58,200 miles. when you compare those numbers to the 155,000 mile oil, the wear metals were approximately 3-times higher thus demonstrating that even if the WS transmission oil had been changed, the wear metals would have been about the same.  Impressive.

As the transmission appears to be operating/shifting perfectly and the WS oil analysis produced no "off the charts" wear metal analysis, I will go ahead and do multiple drain/fills to freshen the WS transmission fluid.       

is250-transmision.pdf