If my Buick sits about 12 hours, the vehicle will hardly move forward when put in drive; But starting off in low for a short distance and shifting it up to drive, the transmission works fine and no slippage. Can this be fixed without a complete transmission removal and teardown?

Thank you

I would take it in ASAP and have it checked out. A '94 LeSabre I just bought had the same problem. After about 10 miles of driving it finally would not engage into any forward gears. I had to have it towed in to a shop. Of course, I knew about the transmission problem; I'm having the freshly rebuilt 4T60E pulled out of my recently departed '93 Park Avenue and putting it in the LeSabre.

I had a 93 Silhouette that did the exact same thing.
I've heard that it is casued by wear on a clutch plate or something like that....and I think they said you might as well rebuild the whole thing while you're in there.

in was on a forum, not from a mechanic, so YMMV

I have seen them do that for several years before overhauling. Try putting it in reverse first until it enguages, then shift to drive. It has the same effect as going to first. You have low line pressure usually caused by the pump or filter. Usually the problem you refer to is more prevelent during colder weather when the fluid is thicker,

Sounds like a good place to start is replaceing the trans filter and fluid. Continue like tou are and it will definitely need to be rebuilt. Just my 2 cents.