Hi Scotty huge fan here. I bought a 2006 Lexus IS250 recently which now has 186k miles. About 5k miles ago I did a drain and fill of the transmission fluid and added Lucas transmission slip fix to help rejuvenate the old fluid. I don’t believe the previous owner did any changes to the transmission fluid. However recently the transmission is shifting a little rough. It’s noticeable now when it was shifting smoothly before. The mechanics I go to recommended I change the fluid again, but I am not sure if that is the best idea. I want to keep the car for as long as possible so what do you recommend? Thanks again and I hope to hear back soon!
Change the ATF again ASAP.
Use the OEM fluid, drain the full amount (if it’s not possible to do, use an extractor) and fill it up with new fluid (if I’m not mistaken, verify before putting in any fluid: it’s about 9 quarts of Toyota ATF WS)
I’d do it multiple times to make sure you don’t have any gunk left over from that additive in there.
Probably also a good idea to do a “relearn” on that transmission if possible.
Because of that additive (I’m assuming it’s the thing that caused it, might be just the fluid change - no one knows) you’ll probably end up needing a new valve body or maybe even a full replacement / rebuilt.
additives are only for when your transmission is broken and you ain’t planing on repairing it properly - when there isn’t anything to loose and not on a perfectly working one.
this transmission, AISIN TB-65SN IMO was quite weak to begin with. Anything form solenoids wear to the front planetary wearing out - as I see it, Lucas usually “helps” with friction plate wear (not something that is typically an issue on your car form what I’ve seen)
so not only is it an attempt to fix what’s probably not broken, you might be causing different new issues.
