Wrong automatic oil?

Hello dear people, I have now driven the new gearbox at my Continental and eliminated all the errors all around. But the automatic makes trouble. When switching up the machine is relatively strong, when switching from the 1st to the 2nd gear. As oil Mannol Dexron III Plus was filled with Mercon V specification and now I wonder if it is also the right oil. I have telephoned with Mannol and got another “Universal Oil” recommended. According to Ford, Mercon must be in there This was changed as far as I know, so that everything that should run with Mercon should now run with Mercon V. The US car dealer from my vicinity was not sure either and I meant to try it with Lubegard Platinum first. This could do wonders, but I really don’t believe it. But well, I have now tipped it in and drove about 80 km with it and noticeably changes. Someone knows this oil and knows if it might be the wrong thing for my gearbox. ? I have built an AX4N. I look forward to your answers.