Hi Scotty! I drive a automatic 2016 lexus IS 350 AWD. I bought it used from a Lexus dealership with 75 500 km's. I'm currently at 107 000 km's and I didn't find any record of transmission services being done through out its life, so I thought it would be time to do it. I had 3 transmission drain and fills done at my local toyota dealer with about 1000kms in between (give or take), and noticed it is still quite dirty! From what i read online 3-4 should be plenty but I was pretty disappointed with the results of the 3rd time. Especially at 184$ a shot! It's still a dark brown/red colour and not transparent in a glass cup. Should I get another drain and fill done or just do one every couple thousand km's?
Thanks!
- -Austin
Please do not double post, give it time to go through the system. Thank you.
Mathematically speaking, it’s impossible to get rid of all the Dirty fluid by drain and fill. Practically speaking, at some point there should be so little old dirty fluid left that it is inconsequential. it may take several times if you don’t drop the pan, clean the glop off the magnets, And either replace or Spray clean the strainer screen. There’s always a bit of dirty fluid in the bottom of the pan after draining, in addition to what’s in the torque converter, the cooling lines, etc. I keep watching videos of guys running the old fluid out of their lines by running the motor, but I’m not brave or ambitious enough to try that.
By my calculations, if you are replacing one third of the fluid with each drain and fill, you will still have 30% old fluid after 3 drain and fills. After 4 you still have 20%.
did you replace the filter?
No I didn't. From what I've read and what the dealership told me apparently you don't need to replace the strainer as it only catches bigger particles when it's running, which settle back to the bottom of the pain when it's not. I'd still like to get it changed for the peace of mind but apparently its unnecessary/a waste of money so I didn't bother.
- There's no simple answer to this question, unless you like doing really freaky math, haha. Modeling this accurately would probably require creating and solving a complicated partial differential equation. It would be a more simple ordinary differential equation if it were being drained from one end and refilled from the other simultaneously (flushing), which we don't want to do. You'll get 1/3 new fluid in on one change, but the next change will take both old and new fluid out at some unknown rate. Really, changing it anymore than 2 or 3 times is wasting time and money. Scotty's says to change what comes out in the pan every 40-60k mi.
i did it 3 times so far on my 2010 accord 4cyl going to dothe 4th on my next oil change and do the filter as well. just dont flush it
