I have a 2003 V8 4Runner (with trans fluid dipstick) with approx 160k miles. I haven't had the vehicle too long and so am uncertain as to the history of ATF changes. However, the fluid on the dipstick does look nice and pink/red in color. I am looking to change the fluid, however, am getting some varying advice on what should be done. I have read/heard that in general it is not a good idea to replace all your transmission fluid (eg. a full flush) if you are uncertain how regularly it has been changed. I believe the reasoning here is that replacing all the fluid with new more viscous fluid could cause problems or perhaps the flushing action could dislodge shavings etc. My Toyota dealer offers either a full flush (with some sort of machine) or a drain/fill. They recommend the full flush in order to ensure all fluid is the right stuff and they haven't really heard of the flush concerns that I mentioned. I decided to call another dealer and their service guy said given age etc of vehicle, he would not recommend a full flush (saying something for example about could dislodge something unwanted from torque converter). He recommends drain/fill but also says that would replace about 80% of the fluid (I didn't think a drain/fill would replace so much). A couple other calls got me yet more mixed messaging about whether a full flush is appropriate. And another that says to pull pan and replace filter?
What are the experts on this forum doing in similar situations? On one hand a full flush would ensure you get all fluid replaced with the right stuff (who knows what is in there now even though it looks ok), however, I wouldn't want to compromise the transmission in any way.
What are the experts on this forum doing in similar situations? On one hand a full flush would ensure you get all fluid replaced with the right stuff (who knows what is in there now even though it looks ok), however, I wouldn't want to compromise the transmission in any way.