In fact, it has to be said that more and more car manufacturers have realized the necessity of oil change and many of them already demand it – for example, for certain Audi models, Mercedes AMG vehicles and many other car manufacturers.
At the same time, the recommendation is “lifetime oil”. Unfortunately, no one talks about how long the transmission’s life is without oil change. And if the life of the oil is be over, then the rule is that the transmission’s life will be over relatively soon.
Depending on the type of the transmission (CVT, DSG, AT) and the intensity of use (city driving vs. highway, hot vs. cooler climate), the transmission can work smoothly for a few hundred thousand kilometers. At the same time, we have seen transmission that already have strong wear marks after the first 70,000 – 100,000 km.
Most car manufacturers do not make their own transmissions (except for Mercedes, Renault, US Ford, GM, partly Toyota, Nissan and Mitsubishi), but use the production of transmission manufacturers. That is why car manufacturers do not offer any more spare parts for gearboxes. The sad truth is that it is more economically feasible to sell a new transmission than to try to repair it at the dealership.
Transmissions have become so complicated that car manufacturers do not have the real resources to train their highly qualified staff and buy special equipment around the world.
If in the old days the transmission could be repaired by every man in the shop, then a set of equipment with a price of over 150,000 euros is needed for modern transmissions.
The reason why car dealers do not want to maintain a transmission is their complexity and potential problems. The oil should only be exchanged in these transmissions that are still in order but testing of transmissions (not to confuse with reading error codes) requires experience that most services do not have.
Changing the oil in a poor transmission can make the problems worse, because the viscosity of the new oil may already be another compared to that what was used for a very long time. Apparently, no dealership wants that kind of a PR campaign.
One can also point out the car manufacturer’s insignificant margins on spare parts. It is not uncommon for the original oil to cost 60-120 euros per liter and over 100 euros for the filter in the dealership. How do I justify to a 7-year-old vehicle owner that the transmission needs maintenance for 800-1000 euros? At such a price, it is really more sensible to have the transmission repaired.