I have 1985 380sl, the transmission operates pefectly when the car is cold. When it warms after 5 to 10 miles, the transmission has trouble shifting up into 3rd + gears. Will a fluid and filter change help this?
Or any other suggestions.

a service may help, what i have seen is when the filter gets old, the actual filter inside becomes dislodged, and when it is hot will raise and block the fluid inlet causing an upshift problem