code58

Thanks for sharing your story. I feel it shared good advice and perspective on RX trans. issues.
One thing people don't realize is that there are a lot of strange things that go on with engine and trans. (and other things too) failure that lead to a replcement with a rebuilt unit. Sometimes those strange problems are passed along undetected in the rebuild process. I don't particularly like rebuilt parts because of that and the unknown concerning the quality (rather lack of) in the parts used to do the rebuild. I wish I had a nickel for every "rebuilt" product I've seen that was bad right out of the box (packaging). It's a tough call on what to do when needing a replacement trans for an RX. The ONE choice I wouldn't make... a used one, too much of roll of the dice!

hypervish

The U140 is not a bad transmission at all. It actually is a great transmission, the issue is that Toyota put that transmission into the RX without doing any upgrades till about 2001/2 and because of bad programming. Which is why if you change the fluid regularly you can prolong the life of the transmission by ensuring that the fluid doesn't get burnt. My transmission doesn't burn up fluid like others have experienced, but I also change the ATF every 15-20k miles without fail.

The U140 is used in many other applications of Toy/Lex vehicles, and they last forever. Many with over 300k, 400k miles all on the original transmission. Because they are all lighter cars. The transmission was made with those cars in mind, not the RX. Also, those cars do not have the strange fuel sipping programming as the RX. (not that this programming really helps the RX get outstanding FE)

But that's not to say the U140 cannot handle the weight of an RX. It can, and it certainly with the proper maintenance. The U150 in the RX330's is essentially the same as the U140 with really just an additional overdrive gear, there aren't many other changes. And, they are standing up fine! Because they have DBW which prevents damage to the transmission.

The issue coming into play with the U140's in the RX300, IMO is the programming of the ECU. You will notice that as you come down to a stop, the transmission will drop into neutral at around 15 mph. This is because it's programmed that way to save fuel. It will also upshift into the highest gear as soon as you let off the throttle. They did this to improve fuel economy and emissions as well.

This type of programming leads to excessive wear, the transmission is constantly shifting especially in city driving. The worst though is when it drops into neutral, because there's a huge strain on the transmission if you get back on the gas without coming to a full stop. Since the transmission is then forced to shift into 1st while moving.

I'm very careful when driving and feel for the transmission to shift into neutral when I slow down. So that if the light turns green and I'm still rolling I'll very, very gently hit the gas to get the car back into gear without putting a ton of stress on the transmission. Once back in gear I'll accelerate normally.

For this reason, it is a good idea to use the "Snow" function when stuck in traffic so the transmission isn't continuously going into neutral and continuously being forced into 1st.

rxda90

I am the new owner of a 2000 RX300. Having lurked on these boards for a little while, I can say that the one thing I'm concerned about is the longevity of my tranny. It has 144k miles currently.

I do have complete service records, which indicate a LEXUS DEALER TRANSMISSION FLUID CHANGE OUT at 30k miles. Unusual. I pulled my disptick this morning and found the fluid to be bright pink, and there is no burnt smell whatsoever. Counting my blessings I guess ...

I had planned to do a transmission fluid change, but am now hesitant to get in there are fiddle with it at this point, since I am experiencing no trouble, and there is no indication of problems on inspection. You know, "if it ain't broke ..."

Would the gurus on this board still recommend that I begin a regimen of periodic fluid changes?

salimshah

Just to set the record straight, I am among the least educated on the transmission. I let Lexus maintain mine till 100k and since then I do drain and fill with drop/clean around 120k. I certainly kep engine rpm around 2.5k and nver go near 3k till the vehicle is warmed up. I have done occasional towing (not enough to learn how to reverse)

Salim

LA4Mead

I normally agree with this wholeheartedly... However I would like to add that this was not my experience with my RX300 as an original owner. The original transmission in my car did burn fluid badly from the day I picked the car up new. Being the picky wrench head DIY even though I had a new Lexus, I would always check the car over myself even (especially) after picking it up from dealer service. Pulling the dipstick revealed the fluid's condition which shocked me, and I had to insist on paying at the dealer for trans service, which they insisted was completely unnecessary.
I had the fluid changed three times while the car was still under the new car warranty, so it was done often. The third time was at the local Toyota dealer and they documented the debris in the filter and pan in addition to the poor condition of the fluid. The transmission normally shifted smoothly, but in unusual circumstances it had a slamming back-and-forth shift when it was cold - colder than it usually gets where I live, so that rarely happened. But this was documented on several trips for warranty service where my regular dealer would gladly ticket the car for service and return it to me "no problem found".
I found online that there was more than one TSB issued by Lexus for this problem on early 2WD RX300's, oh well. One more trip, this time to a different dealer for trans service right before the powertrain warranty expired so I would have the problem documented in case of failure. They inspected and got Lexus on the line and offered to replace the transmission without any fuss from me. So there were in fact some RX300 transmissions that had issues right from the start regardless of having service with fluid changes above and beyond the official Lexus "no service needed until failure" policy.

hypervish

You're right, that transmission was clearly defective and some of them definitely left the lot like that. It's a good thing you kept an eye on it.

However I think those issues are not related to the typical no reverse or no forward gears failure of the transmission.