CVT gearbox service

[JimD73]

Hi, could I ask for some advice please. I have just bought an 06 b-class CVT w245.
The previous owner said he changed the gearbox oil every 2 years regardless of what the service schedule stated.
Is this something other CVT gearbox owners recommend?
Also, i assume there is a filter somewhere that also needs changing at the same time? If so, could someone confirm its location please.
Many thanks, Jim

 

[John]

I don't have any experience of Mercedes CVT (but from what I hear, they can be a problematic pile of shyte!).

Changing the fluid seems to be the recommended way forward to keep them running well - regardless of what MB tell you (remember MB once told us all that "sealed for life" was a good thing (albeit for them) except they meant the life of the gearbox while the car was under warranty as they couldn't give a flying after that and might sell more new gearboxes as a result).

My experience comes from my other half's Juke. CVT died at 2y10m and 22k.

"Revised" version of the same gearbox fitted under warranty (as the facelift version couldn't be fitted to the pre-facelift cars apparently).

All was well beyond the same mileage / age of initial failure gearbox but I noticed it started to get a bit sloppy and just a bit shyte in the last 6 months as it approached 4 years from said warranty replacement.

In the end, I forced Nissan to change the fluid as it just went over 4 years and they did and it has been a lot better since.

Initially they declined stating it wasn't necessary.

However, we had the car from new and I saw that originally the service book stated the fluid be changed at 4y or <whatever> miles but after one particular service, Nissan stuck something over the top of this original schedule with a new schedule where the fluid change was no longer mentioned.

In the end, I got it out of the service manager that the only reason they did this was so they could claim lower running costs for the car, and that actually the fluid should really be changed.

Fckers!

So I would do it regardless and if every 2 years means saving the hassle and expense of a rebuild or replacement, I would...

 

[Petrol Pete]

I don't have any experience of Mercedes CVT (but from what I hear, they can be a problematic pile of shyte!).

Changing the fluid seems to be the recommended way forward to keep them running well - regardless of what MB tell you (remember MB once told us all that "sealed for life" was a good thing (albeit for them) except they meant the life of the gearbox while the car was under warranty as they couldn't give a flying after that and might sell more new gearboxes as a result).

My experience comes from my other half's Juke. CVT died at 2y10m and 22k.

"Revised" version of the same gearbox fitted under warranty (as the facelift version couldn't be fitted to the pre-facelift cars apparently).

All was well beyond the same mileage / age of initial failure gearbox but I noticed it started to get a bit sloppy and just a bit shyte in the last 6 months as it approached 4 years from said warranty replacement.

In the end, I forced Nissan to change the fluid as it just went over 4 years and they did and it has been a lot better since.

Initially they declined stating it wasn't necessary.

However, we had the car from new and I saw that originally the service book stated the fluid be changed at 4y or <whatever> miles but after one particular service, Nissan stuck something over the top of this original schedule with a new schedule where the fluid change was no longer mentioned.

In the end, I got it out of the service manager that the only reason they did this was so they could claim lower running costs for the car, and that actually the fluid should really be changed.

Fckers!

So I would do it regardless and if every 2 years means saving the hassle and expense of a rebuild or replacement, I would...

As you stated in your post. This 'sealed for life' carp is just so they can convince fleet managers that their vehicles are cheaper to run. Anyone who has an ounce of sense knows if you have 2 moving parts rubbing together in an oil bath one day something is going to 'give' , never mind in a complex gearbox with hundreds of moving parts. Oil is cheaper than gearboxes.

 

[190]

I'd continue changing it every 2 years if you want it to last and I wouldn't compromise on the choice of oil. It has to be specifically approved for that gearbox.

 

[wongl]

I have a lot of experience on the MB CVT gearbox having owned the original A-Class W168 for over 10 years from new, then 3 A-Class W169 (starting with a 2006 model) and then a B-Class W245 (with a 2010 model).

With so many CTV models over an extended period (almost 20 years) I have suffered 3 gearbox failures - but thankfully none of them with mechanical issues, only electrical where the wires inside the sealed transmission ECU break off which can be repaired by various specialists (e.g. ECUTesting.com) for a very reasonable cost. The wire breakages causes the transmission ECU to shut down due to improbable speed detected (i.e. the speed signal from the engine does not match the speed signal from within the gearbox). This shutdown of the gearbox actually protects the gearbox mechanically and in fact, as I understand it, results in rare CVT gearboxes with actual mechanical damage!

With regards to the gearbox oil change, this is a now a routine service item every 4 years together with the gearbox filter and sump (rubber) gasket. In mine opinion, there should be no harm changing the gearbox oil more frequently, assuming that the correct grade of oil has used.

The filter is inside the CVT gearbox and can be reached by dropping the gearbox sump which is held in place by a large number of screws. From memory, the filter costs circa £28 from Mercedes. In my experience, the sump screws are typically difficult to remove, and on one occasion I managed to snapped of one of the screws by applying too much force!

 

[wongl]

I'd continue changing it every 2 years if you want it to last and I wouldn't compromise on the choice of oil. It has to be specifically approved for that gearbox.

From my personal experience, I wouldn't recommend over changing the oil beyond the recommend service/mileage interval. It is not environmentally friendly to over change the oil, expensive and actually risks damaging your gearbox (refer to my post above about the risk of snapping off the sump screws) without any significant benifits! Additionally it is a messy job if done properly as the sump should be flush clean of metal debris using brake cleaning fluid.

 

[JimD73]

Thank you all for your very helpful advice. I had read very mixed reviews about the gearbox before buying. The way I looked at it, most cars out there have some kind of issue. I think I will continue to change the oil every 2 years, as it has had a merc service history with a gearbox oil service every 2 years, they must be doing so for a reason.
Wongl, thanks for the heads up about a repair company should the ECU give issues. I had purchased an extended warranty for peace of mind but it doesnt cover ECU's for cars of that age.
The last service was 10 months ago and it was the big service with all filter, oils etc changed, so I have a couple of years before another major service.
Again, thank you all for your help and advice.