Can anyone explain to me the transmission in my '05 Impala? It's a base model with the 3400. Transmission just feels odd... there's four gear positions on the shifter but I feel four shifts up then if I'm on the highway and apply really light throttle it kind of slowly drops the engine RPM way down, like there's either a 5th gear or else the torque converter is real loose and I'm feeling the lockup. Which is it? I assume the latter but don't have any experience with GM's any newer than my dad's '73 Chevy pickup.
Also, I assume that this is good for fuel economy but it is practically impossible to maintain this highest gear ratio as as soon as I have to lift off the gas for traffic etc. or have to accelerate with more than a feather touch on the accelerator it "unlocks" (or shifts down) and RPMs go way up again. Any trick to keep it locked into the top ratio? I can't imagine this constant shifting is any good for the tranny either. Would a synthetic fluid be a good idea, if I can't change the operation of it?
thanks,
nate