Similarly, I went to see 3 doctors and all 3 had different things to say. I became uncomfortable as a result and went on asking different doctors until the final Dr. said to me “ I want you to this test before I give an answer since you are not happy with the other Drs.”
When the result came back, I was rushed into the operating room without an appointment.
All doctors said I was fine and gave their opinions on my symptoms except the last Dr.
That is the exact same experience that my SIL had, about 30 years ago. Orthopedic doctors, Neurologists, Physiatrists, Osteopaths, and other NJ people with medical credentials gave her wildly varying diagnoses for her debilitating back pain–including “it’s all in your head”. All they wanted to do was to “dope her up”.
Finally, out of desperation, my brother took her to Columbia Presbyterian, in Manhattan. The next day, she was in surgery, for 9 hours. The Orthopedists and Neurologists at that hospital figured out–in one day–that she was very close to being wheelchair-bound for the rest of her life.
That emergency surgery made all the difference.
I thought you were supposed to quit when you got the answer you wanted 
That’s where I went and had the urgent surgery.
They are one of the very best, along with Johns Hopkins, The Mayo Clinic, and Massachusetts General.
We can get you in immediately for an emergency transmission service (don’t forget to bring money).
My friend and I are at a restaurant and he’s kinda upset that I’m bringing in my car tomorrow for a transmission fluid exchange.
He argues that on all his Toyotas he’s never in his lifetime ever serviced his cars transmissions and all vehicles performed optically for well above 200k miles.
For instance, his 2014 Toyota sienna was traded in at around 220k miles with zero issues. His current 2021 sienna at 97k miles has never been serviced where it concerns the transmission and he has no plans to.
I told him I’m taking the safer route and that I received valuable advices from this community. He said “ Ok, waste your money “
lol.
Enough already. Stop beating subjects to death .
lol … when it comes to cars, everyone seems to have an opinion. The problem with asking your question is most every transmission is a littel different from the others these days. So the only reply you’d be able to rely upon w/confidence is from somebody who has owned that exact transmission for 100K+ miles , and drives similar to how you drive. The answer also depends on how long/many miles you plan to keep your Lexus before selling it on.
FWIW, I replace my truck’s C4 auto trans fluid every 30-60 k miles by removing & cleaning the pan and cleaning or replacing the filter. It’s also possible (I think) to drain the torque converter (which drain considerably more of the old fluid out), but I’ve never bothered with that. Your transmission is a much different design than mine of course, so I’m just providing what I do for comparision and contrast.
That’s what I’m learning, George. And this topic has help enhanced my awareness on this subject.
I enjoyed the interesting topic.
I think the topic might annoy some because they are already aware of it and I’m just now being introduced to it.
He lives/drives in a mild climate. Customers in my area operate primarily in city traffic with summer temperatures of 110 F and higher.
I have seen many IS 250/300/350 cars and a dozen or more transmission failures. The most common failure is torque converter clutch slippage.
I’ll estimate the transmission failure rate for the older models (2006-2009) after 10 years/125,000 to 150,000 miles to be about 5%.
With routine maintenance the failure rate might be reduced to 3%.
With each service there is a 10% chance the technician will get the fluid level wrong.
With each service there is a 1% chance of causing a fluid leak.
The engineers have studied the benefits of long-life fluid vs routine maintenance.
If you plan to keep the car for 10 more years, change the fluid sometime between now and 100,000 miles.
I’m just going to say this, the more you ask about it and the more people you ask about it the more conflicting info you will get and the more confused you will get…
Over the years, we’ve had a few colleagues who seek advice for a problem
First, they’ll go ask one guy
They’re somehow unsatisfied with the answer, so they ask another guy
Then they ask several more guys for advice to the SAME problem
Needless to say, these guys are annoying and have ZERO respect
And just to make it crystal clear . . . all the guys that were asked gave sound, professional advice
The problem wasn’t the answers
The problem was the guy asking the questions
I have no issue with a 2nd or 3rd option/opinion, I will even go as far as asking the same question over and over again until I get the same answer a few times, but once that happens I am done, I don’t ask another 47 times… you can only beat a dead horse for so long before you realize it ain’t going to work no more…
In this case the OP needs to make a spreadsheet and put the 5 mabe 8 possible answers down, but it is 4 questions either yes or no, nothing less nothing more, take the highest number and go with it… (*4 different yes and one group no, or 4 indi no’s)
I’m out, let us know the outcome in another 100K miles…
Are you trying to get the most from your tranny fluid or the tranny? Exchanging the fluid early is BETTER than exchanging it LATE. Your choice.
Let’s just start ANOTHER “what’s the best oil?” discussion/arguement. Then we can really annoy the members here, and visit already “scorched earth”. 
I’m trying to understand why there are opinions on a critical car maintenance. I thought when it comes to cars, things are pretty straightforward.
Now I know otherwise.
Was reading the comments from car mechanics on Quora last night. Maan, it was hilarious seeing the mechanics disagreeing with each other.
I paid attention to the upvotes on each comments, and the mechanics who advocate for a drain/refill would get 3+K upvotes and the ones advocating for a flush would get only 20 to 100 upvotes.
So from that simple debate I learned that people prefer drain/refill over a flush or fluid exchange.
One thing stuck out to me, though, is that the mechanics advocating for a flush spoke intelligently and non-offensively, and remained professional in their assignment. That appealed to me.
I did already make up my mind on the flush before heading over to Quora; I just wanted to learn more about the fuss and political issues on transmission fluid.
And for those who believe Quora is a cheap or unreliable platform, I would suggest you to give them a chance and look at the contents once more.
I’ve never heard of transmission fluid being a political issue.
See @Nevada_545 's comment above. There are many opinions because one can frequently survive without fluid changes, but changing fluid increases the (already pretty high) odds of avoiding a worn out transmission (but also increases the odds a mistake during servicing). If 90+% of cars can go 100k miles no problem without a fluid change, you would be money ahead to skip the change if you plan to sell by 100k. If you’re interested in 200k-300k, then changing fluid (I’m a fan of 50k intervals because it’s easy to remember) might be worth it, as long as it’s with the correct fluid (some brands are VERY picky, like Honda/Acura, and CVTs must have the correct fluid) and done by a good shop.
My former Lexus dealer tried to extort 15k fluid changes (‘we can’t stamp the service manual otherwise’) for my then-new ES300, I left and didn’t return.
