Using the incorrect transmission fluid can indeed cause various issues with your vehicle's shifting and overall performance. MB236.15 is a specific transmission fluid that is specifically designed for certain Mercedes-Benz models. It is important to ensure that you are using the correct type of fluid for your vehicle, as specified by the manufacturer.

If you are experiencing jerking when shifting to the "D" or "R" position, or if your vehicle is stuck in first gear, it is possible that the transmission fluid being used is not the right one for your vehicle. Using the wrong fluid can affect the transmission's hydraulic properties, which can result in improper gear engagement and shifting issues.

To resolve this problem, it is necessary to drain the incorrect transmission fluid from the system and replace it with the correct fluid recommended by Mercedes-Benz (in this case, MB236.15). It is essential to use the fluid specified by the manufacturer as it is formulated to meet the specific requirements of your car's transmission.

It is important to note that if the incorrect fluid has been used for an extended period or in significant quantities, it may have caused damage to the transmission components. In such cases, it is advisable to have the vehicle inspected by a qualified mechanic to determine if any repairs or further actions are necessary.

Keep in mind that this information is general and may not apply to every specific situation. It is always best to consult your vehicle's owner's manual or seek advice from a professional mechanic if you are unsure about any maintenance or repair procedures for your vehicle.