Transmission Fluid Lasts a Lifetime???

[PeterTorbet]

Just called Milton Keynes Lexus to get my transmission fluid changed and AC degassed/checked (both things I can't do at home). The guy on service gave me a quote for the AC, but said not to worry about the transmission fluid as it never needs changing. On my service records an indy said they changed the gearbox oil at 105,000 miles. Should I insist it's changed (belt and braces) or go with the 'never needs changing' and save a few quid?

[C Mclean]

I’d start looking for an independent garage that has experience of Lexus.

[Herbie]

These quotes are from different parts of a post going on in our sister group on Facebook and may be of interest to you:

Aircon servicing is basically snake oil, designed to make money for the companies who carry it out. I cannot find any advice that is impartial, only advice by companies who actually carry out aircon servicing and, of course, they are going to say that you should have it done every two years or so aren't they?
The aircon system is sealed. Nothing can get in and nothing can get out unless there is a fault or problem of some kind and that will usually manifest itself by the system beginning to make noises or not getting as cold as it used to do. That's when you take it somewhere to have it investigated, regassed, or whatever, but the idea of taking it for a 'routine service' every couple of years is an absolute con designed to relieve you of your money.
Adverts will often say that part of the service is to "take out the "old" refrigerant and replace it with "new"" - but refrigerant doesn't degrade or 'wear out' - it just 'is'. As an aside, my granny's fridge is 30 years old and the refirgerant still makes it cold as ice in there!
The system seals are lubricated by the compressor oil and again, they don't wear out or degrade unless there's a leak and the system loses oil - but again, that would show in not getting as cold as it used to.
Anecdotal evidence from friends and family shows that not a single one of them has ever had a 'routine aircon service' and not a single one of them has ever had aircon problems.

The other chap had come back with a reply comparing AC servicing to "sealed for life" gearboxes. Some say yes, some say no, so the topic went on from there:

Physical gears meshing in the transmission will always shed metal particles, which over time will gather into a metallic sludge and could cause problems. Also, the transmission fluid itself gets contaminated and the friction modifiers lose efficacy, so common sense says that it should be changed and there should be no such thing as a "sealed for life" gearbox.
However, and this is crucial, the manufacturers class "sealed for life" as being the life of the car so it is a finite parameter.
Refrigerant gas - unless something is wrong - does not pick up metallic sludge and does not degrade and if it was opened up in a hundred years that refrigerant gas would be the same as the day it went in. Once that system is charged and sealed, there just isn't anything to service.

[LexIS200Sport]

@Herbie, compared to a refrigerator, the aircon system in a car is exposed to more extreme operating conditions - heat from the engine being one. As over half the aircon system resides in the engine bay, would that not mean that things like the oil would be prone to degradation?

Also, isn't there a "filter" within the sealed aircon system (and I do not mean the pollen filter). If so, would that not need replacing at some point?

Just wondering - please correct me where wrong  🙂

Agree 110% on the transmission side of things. In my books, sealed for life = sealed for 10years/160,000km

 

[PeterTorbet]

7 minutes ago, LexIS200Sport said:

@Herbie, compared to a refrigerator, the aircon system in a car is exposed to more extreme operating conditions - heat from the engine being one. As over half the aircon system resides in the engine bay, would that not mean that things like the oil would be prone to degradation?

Also, isn't there a "filter" within the sealed aircon system (and I do not mean the pollen filter). If so, would that not need replacing at some point?

Just wondering - please correct me where wrong  🙂

Agree 110% on the transmission side of things. In my books, sealed for life = sealed for 10years/160,000km

 

Yup, even told the fella it was 14yr old, 135,000 miles

[Herbie]

1 hour ago, LexIS200Sport said:

compared to a refrigerator, the aircon system in a car is exposed to more extreme operating conditions - heat from the engine being one. As over half the aircon system resides in the engine bay, would that not mean that things like the oil would be prone to degradation?

Also, isn't there a "filter" within the sealed aircon system (and I do not mean the pollen filter). If so, would that not need replacing at some point?

The engine bay is indeed a more hostile environment but as far as I'm aware the refrigerant gas and oil don't degrade or change their composition or structure in any way because of that environment. I've never had a routine AC service done on any of my cars and I've never had an AC problem. I had my previous car for over 10 years and the AC got as icy cold on the day I sold it as it was on the day I bought it, as all my cars have.

Again, as far as I'm aware, I don't think there is any filter within the sealed system but I may be wrong.

I would imagine that statistically you'll cause more problems by opening a sealed system to do routine servicing than occur naturally without interference.

[rich1068]

A while ago I spoke to a member of the Federation Of Automatic Transmission Engineers http://www.fedauto.co.uk/ I wanted a little advice regarding my GS. Changing the transmission fluid was one of those jobs that everyone on forums bangs on about but is usually (imo) dismissed by dealers and independents as unnecessary. Not only did he say he couldn't remember the last time he'd had to work on a Lexus gearbox but also he was extremely reluctant to recommend fluid changes on a high mileage/older car that had previously no history of such changes. Buy a brand new car and change the fluid every 20k, fill yer boots, keeps everything fresh. But start changing the fluid on a gearbox that has been performing perfectly well for the last 15 years/150k miles and you run the risk of disturbing something the magnets don't catch, especially as fresh transmission oil has additional cleaning properties. He also said flushes were a big no no. 

I'm just repeating what he said, obviously it's up to Peter. There is a big BUT. Lockdown had just started, I was really bored, so I changed the fluid anyway  Oh, and there's another but. My car was only 500 quid and I keep that in mind. If I have to throw it away I'll be upset but it won't be the end of the world.

Re: snake oil, air con servicing and transmission fluid changes. Surely if dealers were so keen on relieving you of £££ then they'd offer fluid changes too?

[Howplum]

When I acquired my 1996 80,000 mile LS400 in March, I also asked Lexus Milton Keynes about changing the transmission fluid, knowing it had never been done, but they advised against it on the basis that they had changed fluid at the owners request before and there had been issues thereafter.

When I checked the fluid on the dipstick it was still a nice red colour, so I decided to leave well alone, especially as the gearbox behaves perfectly. When the fluid is brown with a burnt smell is the time to be concerned, so it's best to check the fluid every time the engine oil is checked.

[Herbie]

27 minutes ago, Howplum said:

When the fluid is brown with a burnt smell is the time to be concerned, so it's best to check the fluid every time the engine oil is checked.

Which is great for cars with a dipstick (I mean for level checking, not the driver!) but a lot of cars, especially with the "sealed for life" transmissions, don't have dipsticks so you can't see the colour/smell of the fluid.

[skyway]

if you get it up on a ramp and run the car until the temp of the trans hits 100 (I think) using an infrared temp sensor you can check via the level hole.

This is quite a good guide.