To flush or not to flush?

gb1600e · July 21, 2020

I have had 2 conversations recently asking if my ISF gearbox has been flushed? Well I never knew gearbox flushing was a thing but apparently yes it is. None of the Lexus ISF service schedules mentions flushing and the nice young man at Lexus service department thought I was mad. (No mechanics available to ask).

2 minutes on the web describes the clear difference from just a drain and replace (the clue was in the name) but any of you F'ers in the habit of having your gearbox flushed as good practice ?? And if by lexus do they record it anywhere?

Northern isf · July 21, 2020

Ill be interested in hearing if anyone's actually done this,does make sense though as with BMW's i've owned are supposed to be fitted with sealed for life boxes but yet there's kits to buy that replace solenoids and replacement fluid.

Northern isf · July 21, 2020

Just done a little bit of research, it does seem that quite a few people have done this in the US but also quite a few have not and they have relatively high miles with no issues.

What i've read is its down to how hard you drive your car as overtime a high gearbox temp can break the fluid down apparently, not sure if that will apply so much over here with our nice cool weather though.

Texas · July 21, 2020

Well this is a big can of worms all right!
Regarding Lexus Autoboxes that is.

In the IS250 section ( and in the US on the LOC) there are those who advocate a change at least every 50,000 miles, those that say ‘Drain a bit and replace whatever amount comes out every 5,000 And those that sign up for the ‘For life’ statement!
I don’t follow the ‘For Life’ crowd as I think that was a marketing ploy and the ‘Life’ according to Lexus is different to My version of ‘Life‘. I reckon that Lexus’s version of Life is for as long as they have any statutory/legal Responsibility for the car ie about 10 years. After this amount of time you don’t really have any recourse over wear’n’tear items, and I don’t believe that any type of hydraulic fluid ( that is what is in the gearbox in essence) is not going to deteriorate after that time ( if not before)

4969_LXS · July 21, 2020

Hi gb1600e and Northern ISF,

I recently had my transmission flushed along with a TCU and ECU reset as a last resort by Lexus Wolverhampton. My transmission starting shifting harshly and was doing the odd rev flare between 4th and 5th. Highly recommend giving Wolverhampton a ring as they have experience with mine and were fantastic through the whole process.

The difference is night and day, it now uses less revs on the torque converter when unlocked and now locks the converter from 30mph instead of 55mph. It pulls harder using less throttle and MPG has increased from 21 to 27 on my 6 Mile commute to work.

From the American forums it does not take much of a drop in fluid level for it to start misbehaving. With transmission fluid living a harsh life it's worth changing, after 12 years and 60k miles being worked, it will had degraded.

My car is a 2008 with 60k miles.

For comparison a friend of mine has a M140i. Although a different gearbox brand, ZF recommend changing their 8 speed transmissions' oil every 60k. Yet BMW along with every other manufacturer say it's sealed for life.

There's a chap on YouTube who has an hour long video on how to remove our gearbox's sump, filter and replace, along with the oil and oil level setting procedure.

Hope this helps

Northern isf · July 21, 2020

1 hour ago, 4969_LXS said:

Hope this helps

thanks for the input, ive been reading into it for a good two hours and have made my mind up to get the work done as mines a 2008 with 70000 miles so in my mind prevention is better than the alternative.

4969_LXS · July 22, 2020

No problem,

I agree, it's worth doing as preventive maintenance, even if Lexus haven't got it down to be done. The transmission has all the components and features included in its design to be serviced, the oil itself could be in good condition but it still ends up with metal and clutch material floating in it from normal use.

Another thing that may be of interest from my experience.

When it gets done, get them to have a good nosey around the gearbox. When the dealership initially checked my gearbox prior to changing the oil. They found an oily substance by a connector on the transmission, they've had another ISF in before with a similar substance in the same place that corroded the connector, I managed to catch mine early by the looks. They didn't divulge into specific locations of the connector, I can't help on that front I'm afraid.

gb1600e · July 22, 2020

Interesting insight there@4969_LXS How much were lexus charging for the flush, if its quoted separately. On reflection agree with @Northern isf to have it done as a proactive step although its something to have done additional to a major service I think. Or maybe by a reputable local / specialist.

4969_LXS · July 22, 2020

Hi @gb1600e, with my car being under warranty at the time, I was just charged for the oil which came out to £50.48. They used 4 litres of WS (world standard) transmission fluid.

The exact process of how they do it I'm unsure of.

There's a couple of methods from looking on the US forums and on YouTube.

1st is a simple transmission sump drain, refill and re-level, changes about 2-3 quarts of old fluid with fresh fluid, and can be repeated numerous times to dilute the old fluid with new. Probably the method they used

2nd is a transmission sump off and filter change which will change roughly 5-6 quarts of fluid with fresh, as we can't change the fluid that's sitting in the torque converter and various other places. You can buy a filter and gasket set on the Web, from memory it comes from Germany. It's not OEM but quality looks relatively on par. See video below, it's an hour long but you can skip some bits, worth watching through though as it goes into good depth. If you have ramps and some technical ability it doesn't seem that bad to do at home or at a mates garage etc.

Best bet is to repeat the sump drain multiple times. Less risk involved and should be cheaper.

I agree with you guys @gb1600e @Northern isf it's a proactive step and in my opinion is good practice and care. I'm a little surprised it isn't noted in a major service. I have read somewhere that it is either checked, replaced or maintained at some form at 120k miles.

Northern isf · July 22, 2020

Well im quite happy about this being brought up as there is also the coolant leaking into the transmission issue so best to get everything checked, think everyone with an ISF should at least do a bit of research online as it could very well be the end of the cars life if either one of these issues raises its head.

4969_LXS · July 22, 2020

@Northern isf definitely. The radiator and water pump is next on my list.

I'm currently in process of removing, polishing and refitting the rear exhaust diffusers/tips. Screws have gone rotten so just waiting on those. To quote Johnny cash "one piece at a time"

my radiator doesn't seem to have much corrosion on the outside. With it having a full Lexus service history in theory it should of always had the Toyota long life coolant in the system, so it shouldn't be too bad on the inside, should hold out for its major service in December.

I'll be looking to have them done then, along with a new auxiliary belt and tensioner. Although they are fine, I'd may aswell whilst the front is all off. If the labour is mental I'll DIY.

A YouTuber called Lam Le has done a radiator and pump change on YouTube. Could be done from home. Location, ramp, tools and expertise dependant.

Hopefully we have some car meets soon, was looking forward to attending some and meeting you guys in person.

Sorry to digress on this thread.

July 22, 2020

I will be looking to get mine done between 50 to 60k

Oil getting mashed between gears does break it down. Wish it was easier as I would do it every 20k then.

Will be keeping an eye on how you isf (tip of the spear) owners get on.

Sent from my Pixel 3a using Tapatalk

Northern isf · July 22, 2020

5 hours ago, 4969_LXS said:

water pump is next on my list.

I caught this just in time! it had the trademark pink residue was quite pricey if i remember rightly ill have a look in my service documents tomorrow and let you know.

Toothy · July 23, 2020

11 hours ago, Northern isf said:

I caught this just in time! it had the trademark pink residue was quite pricey if i remember rightly ill have a look in my service documents tomorrow and let you know.

Was the residue around the pump housing/seal?

Northern isf · July 23, 2020

8 hours ago, Toothy said:

Was the residue around the pump housing/seal?

it was yes

d3ron · May 31, 2022

Thought I'd update this thread as I decided at 116k it would be prudent to get my gearbox 'serviced'

I mentioned it to Lexus Birmingham and they didn't seem too sure, so I contacted Lexus Wolverhampton.

They quoted 2 hours labour and 4 litres of gearbox oil.

My MOT was due so had both done today. I'll monitor how it is in daily use, but glad I had it done.

BTCC_ Racer · June 2, 2022

I had my gearbox serviced, I changed the filter inside. The original filter was clean and so was the Tramission oil. Mine took around 6 litres. If im honest it feels the same lol.

Las Palmas · June 2, 2022

If the quality of the materials in the gearbox from Lexus is in far superior compared to all other gearboxes and the oil is likewise better than any other oil on the market then maybe service interval should be more than double of the same in all other cars from all other brands.

As engine oil needs to be changed more or less like on all other cars, above mentioned seems little likely.

A hybrid car will have the engine running less than a full combustion engine car, but still needs regular oil change.

Gearbox oil is not having such a hard life as the engine oil, but few will believe in the fairy tale that gearbox oil never needs to be replaced. When the salesperson tell that the oil will last for the life of the car, it may be right. Most of us do not have a car much more than what Lexus think is the lifetime of a car and should a gearbox need to be replaced when the car is 15 or more years old, not many of us believe Lexus will cover that.

The right oil, the right filter, the right treatment is what any car need and Lexus make some of the best cars. So, if we want to keep our cars longer than Lexus want us to, we must take care of them.

Lexus want a good reputation, but do not forget: Lexus also want to sell new cars.

ubersonic · June 4, 2022

On 7/21/2020 at 7:12 PM, gb1600e said:

I have had 2 conversations recently asking if my ISF gearbox has been flushed? Well I never knew gearbox flushing was a thing but apparently yes it is. None of the Lexus ISF service schedules mentions flushing and the nice young man at Lexus service department thought I was mad. (No mechanics available to ask).

The ISF service schedule requires inspection of the ATF every 30,000 miles, but replacement isn't something that needs to be done unless that inspection reveals issues.

As others have noted Lexus/Toyota claim the World Standard ATF fluid used in their modern transmissions is for lifetime and should never need replacing, however this is where the Ship of Theseus sails into dock. For those who have never heard of the Ship of Theseus, it's a ship from Greek mythology that belonged to a guy named Theseus (shockingly) and the basis of the story is that the ship remained docked for so many centuries that every single piece of the ship had been replaced, thus raising the question of if it was the same ship Theseus had sailed on and if not when it ceased to be so. The relevance here, is that a Toyota/Lexus transmission with WS fluid will automatically have some fluid replaced over time because the fluid will outlast the radiator and replacing that will require adding ATF, it will outlast the exhaust manifolds and replacing them (without bodging) requires dropping the engine and thus topping up the ATF, as does a number of other mechanical works which will be done in the vehicles lifetime. So while they say the fluid will last hundreds of thousands of miles, they do know that it won't all have to as it will be topped up before reaching the moon.

Obviously whether Toyota can be trusted in their assertion that (unless something happens to it) this fluid will outlast the vehicle it resides in has been debated for years, usually on American forums where they're used to their Chevrolet/GM slushbox transmissions requiring their Dexron II/III to be replaced at regular intervals. Now it's not fair to say that racism has played the biggest factor in the debate, but it has not not played a big part as the refusal to accept the idea the Japanese could design a better gearbox/fluid than a big US manufacturer was definitely a factor in the poo-pooing of Toyotas claims back in the early 00s when the LS430 was one of the only cars with WS fluid transmissions.

As for changing the filters/fluid, the strainer/filter/whatever you want to call it will never need changing as it's so over engineered that the gearbox would need to have disintegrated in order for it to become blocked enough to affect performance (obviously it can be done during fluid replacement, but it doesn't need to be unless something has already gone wrong with the box). For fluid replacement, it really needs to be done by a Lexus/Toyota dealer, this is because doing it properly requires raising the car on a lift and monitoring the process with Toyota diagnostic software. This can be bodged on a driveway, as the car is capable of flashing the ATF light to display fluid temp if you put it in a special mode by moving the shifter in a specific sequence, but it would require you to be working underneath a running vehicle on axel stands. In addition the fluid used for replacement must be Toyota WS fluid, this is a computer controlled transmission and its operational parameters are set based on the operational pressures/temps of that fluid (you could use other fluid but the result would be worse than if you had never touched it).

At the end of the day though it's completely up to you if you choose to have the fluid changed, if you don't have faith in Toyota's claims it may be worth getting it done just to set your mind at ease. Personally I had the WS fluid/strainer changed on my LS430 at 211,000 miles because I was dubious about the claims and had read the stuff on US forums, the fluid/strainer that came out was still just as good as the stuff that went in.

NB: If you use your ISF for towing you need the fluid replacing every 60k, this is normal for WS fluid boxes they just don't put it in F manuals because if you use them for towing you're a heretic.

d3ron · June 4, 2022

Those of us of a certain age will recognise the analogy of 'triggers broom'

It's not that I distrust Toyota, but the owners before me. Plus my car was the Evo review car.

I have noticed smoother/qukcker gear shifts from cold in the few days It's been done. Although I expect the gearbox has been reset so it's probably in learning mode.

Pielight · December 15, 2023

On 6/1/2022 at 12:02 AM, d3ron said:

Thought I'd update this thread as I decided at 116k it would be prudent to get my gearbox 'serviced'

I mentioned it to Lexus Birmingham and they didn't seem too sure, so I contacted Lexus Wolverhampton.

They quoted 2 hours labour and 4 litres of gearbox oil.

My MOT was due so had both done today. I'll monitor how it is in daily use, but glad I had it done.

Nearly two years on is there anything to update on? I imagine there's no further noticeable change since you gave update a couple of days after getting the fluid changed. I don't suppose you recall the cost? Thanks

d3ron · December 15, 2023

It’s not been driven much over the last couple of months as it’s up for sale.

But I’ll get some quality time in it over Xmas, so will give my updated thoughts. I’ll try and see if I can find the receipt for the cost. There’s a lot of them.

H3XME · December 15, 2023

7 minutes ago, Pielight said:

Nearly two years on is there anything to update on? I imagine there's no further noticeable change since you gave update a couple of days after getting the fluid changed. I don't suppose you recall the cost? Thanks

a couple of hours of work and oil, you're looking at sub £300