450h gen 4, 4th year service

[goody]

Hi

booked in for our 4th year Lexus main dealer UK service.

looking at the service plan, the following basics will be replaced BUT when does the transmission oil and the diff oil get replaced as just says replace as required???  Model dependant  not a fixed year.

previous RX400h had a year it needed to be replaced, OIL only has so many years before it needs to be replaced so surely Lexus have to change it sometime.

But when????   Model dependant but cant get a definitive answer.

Anyone know

many thanks 

[Herbie]

As far as I know, they don't change it because the tranny is "sealed for life" which, as we all know, is not really 'a good thing.'

It's a bit of a difficult one really because if you have an extended warranty on the car but then proceed to change the fluid yourself because they don't, it would most likely invalidate the portion of the warranty that relates to the tranny - which is probably one of the most expensive items on the car and the reason why you have an extended warranty in the first place.

[GS300h2014]

Should one replace a transmission's oil? There are 4 types of gears: 1.Auto box  2.Rear differential  3. Manual box  4. Sun & planets hybrid box.

My sentiment is that only the first 2 need oil changes. Its not obvious to me why you would want to change the hybrid's oil; there are no wearing clutches or combustion fumes to contaminate the oil. I can see the need if a bearing or gear failed. However I stand to be corrected/educated.