My van has around 190,000 miles on it. There are no issue when the engine is cold. However, when it gets warmed up, some transmission issues start happening and the shifting becomes hard as if the van is under load. The vehicle doesn't burn oil. There are no leak either. What could be the problem?
When it is warm, your transmission fluid may be leaking past seals in the transmission and this is due to wear and the transmission would need to be overhauled or replaced to fix the problem. You may be able to add an additive to the fluid that may help but do not change the fluid or it may get worse. Have a certified mechanic inspect your shifting issue and let you know what repairs need to be made.