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I've had my '08 IS250 since Feb. '12. Got it with 33k miles on it and it's been a dream to own up until recently.

I keep getting conflicting (and very frustrating) info when it comes to the transmission and fluid and whether or not to change one or both.

Over the past few months it's been slipping in 4th. If I'm on the highway and it downshifts it will completely overshoot the revs, hit 7-8k RPM and then catch with a dramatic jolt. The first time it happened I thought I got rear ended. I have been able to keep it from doing that again by watching which gear it's in and anticipating when it is going to slip in 4th. Yesterday, after backing out the driveway I put it in drive and it made this grinding noise for about 3 (very long) seconds. I asked my mechanic and he said it sounds like the fluid just needs to be replaced. This guess was concurred by another friend of mine who is knowledgeable in auto repair. I call a few shops and am told that "now that I have so many miles on it I do NOT want to replace the fluid." No one could explain why but two different Service Desk people told me the same thing. I've also been told that the transmission fluid is "lifetime." I am scheduled for a diagnostic in the next few days at a Toyota/Lexus specialist shop to get a clearer picture but...

WHAT IS THE TRUTH??

DO YOU CHANGE THE FLUID OR NOT?!

**UPDATE ONE**
So I took the car to the mechanic. I picked this shop because they had hundreds of tremendous reviews on Google. I described the problem to the mechanic and we took it for a test drive in which he drove for about half an hour. Since this problem has started I've been babying the throttle. I don't accelerate hard anymore and will watch cruise control like a hawk on hills. He drove my car like I haven't done in months, accelerating hard through 4th and -- NOTHING. The bastard didn't slam into gear even once. He said it sounds like it may need a flush but also gave the caveat that "if it's the transmission, that's it. No amount of flushes will fix anything" which makes total sense.

He hooked up the scan tool and cleared a couple of unrelated codes referencing the intake manifold, we're waiting to see if those come back.

He said he would like to keep it overnight and see if he can replicate the problem to better diagnose from there. This happens to work out since we'll be going out of state for a few days. I told him about a salvage yard that I found that had an '08 IS 250, his response was that he wouldn't put it in because we have no idea what the life of that trans was and he can't warranty the work. If it didn't move after he installed it then I would be responsible to have it removed and replaced. I told him about the "lifetime fluid" thing and he said that was BS. He also said he checked for "updates" regarding the "flare ups" but didn't find anything. I will update once I hear something new.

highrev6

Jersh

That sucks man. I just bought a 08 IS250 about a month ago with 137k for $7700. I paid extra for a 2 year 25k mile warranty just in case something like this was to happen. Update the post with what the specialist say if you don't mind.

Hope everything works out in your favor.

Gville350

iTrader: (10)

Cheapest option would be to do the fluid flush of course. But likely, since you've already experienced issues, new fluid won't fix it. Start looking for a good, used replacement trans if the fresh fluid does nothing.

MedicalDoc

Flushing the transmission on a car with your miles? Generally, there are 2 opinions:

1. it will dislodge something
2. no it will not

Safest bet would be to do a series of drain and refills, which in a sealed transmission, has it's own set of issues.
Plenty of information on CL on how to do this.

E46CT

Dislodging stuff is an absolute myth. It's just a barnyard myth people repeat--that's why they're not able to explain it to you. Not to say that a fluid change will fix your problem cause it likely won't. Your clutch packs are likely toast for that particular gear.

As a general rule, there is never harm in changing any lubricating fluid in any part in any car at any time or any mileage.

I always say change all fluids at all times in all cars ALWAYS. No exceptions.

HTH.

primavera

Truer words have never been spoken (!)

Mrfix

This topic has been beaten to death on this board and others. There should be a sticky at the top that says "Change your Transmission fluid". I feel like the consensus was to change/freshen your transmission fluid every 30-60k miles depending on what kind of driving you do (it is a simple procedure to drain the pan and refill once a year to keep fluid fresh). It may be too late for this transmission you have but the next one should have the fluid regularly freshened in my opinion. I did the drain the pan thing 5 times and on the 5th dropped it and changed the filter/Screen whatever. I will now will drain pan and replace fluid every year when I do my oil change.

Here is a small guide I did for informational purposes. I had the fluid analyzed at Blackstone Labs and they said it was still good at 90k miles (initial fill) but understand this car is all highway miles without any city driving. DFW does have extreme heat so 6 of 1 and 1/2 a dozen of the other....

https://www.clublexus.com/forums/is-...ne-report.html

Typically if changing the fluid or flushing the fluid ruins your transmission then it was on its way out anyway. I don't like flushes because from what I understand if it is pressurized it can harm the transmission. If you're already experiencing problems then a fluid change likely won't help. Best to pick up a low mileage used Transmission at a wrecker and put it in.

Here is some info from Amsoil.

https://www.amsoil.com/newsstand/aut...remium-fluids/


Fill for life?

I should mention “fill-for-life” transmissions, which are becoming more common as OEMs continue to look for ways to simplify (dumb-down) vehicle maintenance. Most don’t even have a dipstick for checking fluid. On those that do, they can be located in hard-to-access areas. In these cases, check a service manual for dipstick location and instructions for checking the fluid. Although the transmission is designed to be “filled for life,” that typically means fill for the life of the warranty. It’s just as important to service these units and replace the fluid once in a while to ensure the transmission lasts as designed and gives you years of solid performance beyond the OEM’s warranty period.



CHANGE YOUR TRANSMISSION FLUID, it is necessary if you will be keeping the car for longer than the warranty.

Keo

iTrader: (9)

The Truth is NOT.

From my very own experience and same issue with my transmission that you clearly describe. Don't waste your time with this whole Fluid talk thing and all other people telling you about it. The tranny is clearly dying.
What you should do is :
- Find yourself a good low used Tranny
- Grab 6-7 bottles of new tranny fluid from Lexus Dealer
- Find a nice shop to replace the Tranny+New Fluid Flush

Trust me. I gone through the same issue before with my car. Done some deep research and even found a person saying he did all the tranny flush. still not going past 4th gear. The Lexus tranny isn't built to last.

MikeyK02

iTrader: (7)

The tranny isn't built to last, because people dont change their fluids since theyre told it is lifetime.

The concept is simple. damn near every other fluid in your car..you have to change...but yet they have figured a way to make a lifetime transmission fluid?

Only a fool would believe that.

HAVE YOU STUFF FLUSHED...Or drain and filled

2013FSport

iTrader: (2)

Fluids from the last 20 years do not varnish and lead to death by fluid change. ATF is very high in detergent. Fluids from 40 years ago used to varnish. Varnish can build up, fill and seal gaps. So as o-rings age and loose elasticity from heat and material quality the trans develops internal leaks, looses pressure and clutches slip and the unit fails. But in some cases varnish build up reduces those leaks and although the fluid has failed, the trans lives and seems to be OK.
Until.....
Fresh fluid being high in detergent would clean out the filled gaps and create internal leaks. That is the past. Let it go!!!

This does not happen any more!!!!! Period!!!
Change your fluid or buy a new car and/or transmission!

XSV

iTrader: (1)

I've drained and filled my transmission fluid twice. First time was at 194,678 miles and then the second time I dropped the pan and replaced the filter as well at 198,573 miles. Didn't have any transmission problems before or after. If you're already having issues, you're transmission is most likely on its way out.

bionictony

best asked on www.bobistheoilguy.com. my suggestion is to try to flush it with vavoline max life atf or if you want oem fluid use toyota atf ws. fluid capacity in the transmission is probably 7-8 quarts and 2-3 in the circulating system. you can release the atf return line to pump out the old fluid. something about new atf with friction modifiers will probably fix that flaring. toyota transmissions are robust. the fluid is not lifetime.

DallasLex

iTrader: (1)

true

DallasLex, I'm in the DFW area also. Do you happen to know anything about "TLS Auto Specialist Service & Repair" in Euless? That's the shop that I chose.

Generally speaking, it sounds like the consensus is leaning slightly more towards changing the fluid which makes the most sense. "Lifetime" anything just doesn't make sense.

Follow up question: any guesses on what harm would happen if I just rode this transmission out? No service, no replacement. The problem is only in 4th but would it grow? Do I risk driving down the highway and then I suddenly can't go anymore?

I appreciate everyone's feedback on a topic that I'm sure has been massacred through the years.