My 1990 Buick Regal has had a problem for sometime now(glad I found this board). When the engine starts to get hot, and reach the near mid-way point of the temperature gauge, the transmission starts upshifting hard, especially when going into 2nd gear.
I had the transmission serviced with new fluid and filter but that did nothing to help remedy the situation.
Could this be tranmission fluid viscosity issue? I figure the only difference between a cold and hot running transmission is that the fluid is "thinner" when hot, right? I've checked the fluid when hot and it still looks good ie. not brown or burnt.
Any recommendations?
THANX