GM had problems with the low quality oem transmission fluid in the they now recommend using a special Mobil 1 synthetic.
Re;
[quote]The base stock of old GM Dexron fluid (19355656) has the ability to attract low levels of moisture, which can cause degradation of the coefficient of friction of the fluid. The new fluid (19417577) has a new GTL (Gas to Liquid) base stock that is able to tolerate more moisture. Shuddering transmissions and torque converters have been recovered with the new fluid. New transmission fluid tests have been developed due this issue to prevent it from occurring with new transmission fluids.”[/quote]
