Hello everyone.

I kindly ask if anyone has had similar issues. I own a Ford S-Max, 2.0 EcoBlue (diesel), 110 kW/150 HP, 2019 model year, with an 8-speed automatic transmission (model 8F35). It currently has 88,000 km. At low RPMs, between 1100-1500, and at speeds of 70-90 km/h, there are slight jerks or vibrations, as if the car is driving over an uneven road. I must note that the oil in the automatic transmission has never been changed because Ford Croatia does not have a specified recommendation for replacing this oil. They claim it is "long-life"! 

During the winter months, I have noticed that in the mornings, the car sometimes does not shift into a higher gear but remains in a lower one (e.g., third gear), and only after about 30 seconds does it shift into fourth and continue driving normally.

Based on my research, I have determined that this problem is common in vehicles equipped with 8F35 and 8F40 transmissions. I contacted several owners of the same vehicle (and other Ford models with the same transmission) and found dozens of similar complaints on online forums and YouTube channels, which points to a systemic issue.

I also contacted specialized automatic transmission service centers, which confirmed that this fault is common and results from technical deficiencies in the transmission. Most service technicians emphasized that the lack of regular oil changes leads to damage to the torque converter, and often the entire transmission. The repair of these components is extremely expensive and technically demanding.

Additionally, authorized Ford service centers in the USA clearly specify a MANDATORY transmission oil change every 30,000 to 50,000 miles (50,000 to 80,000 km), which significantly contributes to the transmission's durability and proper functioning. All German car manufacturers prescribe mandatory service intervals for automatic transmission oil changes at 60,000 km (VW, Audi, Mercedes, BMW, Opel).

Unfortunately, Ford Croatia (EU-UK) has not included such maintenance in its recommendations, which I believe is the key reason for the problem. This is a significant oversight by Ford Motor Company (EU).

The recommended oil is Ford Motorcraft Mercon ULV. Along with it, the Lubegard Instant Shudder Fix additive is added, and the jerking should permanently stop? If it does not stop, the issue is likely with the torque converter.

Have you had similar experiences with this problem, and did you resolve it by changing the oil?

I would be grateful for your response.

Best regards from Croatia!

Sorry to hear that and I don't know anything about this issue as I thought the only problematic transmissions were the Powershift!!!

As lubrication seems very critical on all auto transmissions and any other work is so expensive, changing oils (and filter?) is the cheapest and simplest thing to do however I am no responsible source?
Sorry for thread hijack but I couldn't resist commenting.
Hope you can get an answer and at least I have kept it at the top of the list!