1993 Buick LesabreTransmission takes 20-30 minutes to warm up

Might be the pressure plate .

Is the check engine light on ?
It sounds like the engine temp sensor is not right, but if that were true you should have a check engine light and a code for the sensor.
Have you checked fuel pressure ?

Actually in cold weather that's common and normal. In cold weather it can take up to a minute or two for transmission fluid to warm up, expand and build up pressure. I reside in Minnesota and this time of year that's normal. On really cold days let it warm up for a minute or so.

READ THIS (happy ending so far...):
audi a4 2L turbo quattro, manual transmission with 98,000 KM. Perfect conditions, no oil leaks whatsoever.

Left the car off for two weeks in very cold weather (-10C down to -25C). When I restarted, it started immediately but with heavy rattling noise due to camshaft adjuster not getting enough oil pressure. After 3 minutes of warming up (outside temp.: -12C) at very low rpm (below 2,000rpm), I start moving the car. Still hearing heavy rattle noise. As soon as I pass 2,000 rpm, I get a scary red warning, low oil pressure. Turn off the engine immediately. In 1 minute, I re-start the car and the engine lights check ok, so I drive in first gear super slow (1,200rpm) hearing the same rattling noise. After another minute, finally the noise all the sudden disappears and the car starts running just fine.

Called Audi dealer and they told me that in extreme weather conditions, I should warm the engine for 10-15 minutes if necessary before start moving.
Take away: luckily, I didn't screw up the engine since I was using it at extremely low rpm (easy to do with clutch and manual transmission) until the oil reached full pressure. I am pretty sure now that the problem was leaving the car off for such a long time in freezing weather. All the oil flows back to the bottom, and when I restarted it, the cold oil with high viscosity took a long time to reach all the parts of the engine, specially the camshaft adjusters that are actuated by using oil pressure. Next day, the car started at -9C perfectly without making any noise (as usual). Basically, the longer you leave your audi in cold weather, the longer you might hear the rattling noise until the oil reach full pressure inside the engine. My car took 6 minutes to fix it after couple of weeks in cold weather. This makes sense to me; in fact, in the past I only heard the rattling noise after leaving the car off for a couple of days in the winter.
So far, this has had an happy ending....

Replacing the filter won't do a thing. Flush/replace the fluid.

Your going to need a new battery. This is the simplest fix for the issue. I would also recommend a block heater. Certain models of these basically get mounted inline with your coolant hoses and they constantly heat and circulate your antifreeze so your car is instantly warm when you start it. They do have to be plugged into an electrical outlet but they are worth it in very cold weather.

Just don't forget to unplug them before you leave with the car :)

But for now sounds like the only thing you really need is a new battery. As much as i hate to say it walmart has some pretty good deals on batteries and they usually don't charge to put them in. Worth it especially when its cold.

SHift solenoid pressure switch

perhaps you need a new cap and roter a new spark plug wire set. they don;t like moisture. also check to see if you have any broken or leaking vacuum hoses. the worse case senerio would be that your head gasket is leaking--at cold temps a little antifreeze will enter until everything warms up and it seals shut due to metal expanding. but since you say it's cold weather only--this probably wou;dn't be the case. good luck.

etal for instance expands and contracts due to temperature differences, granted the changes are very minimal but in a machine that has no room for tolerances, these changes can be enormous. Oil is another one, your engine is actually filled with oil on the inside and when that oil is cold the viscosity of it changes dramatically, its like comparing tree sap and maple syrup. And all of these little things play a crucial role for your car.

You must let your car warm up properly before you use it. My recommendation is that you leave it in park for about 5-10min in the morning, just enough to get your transmission warmed up enough for it to work properly, after that you want to make sure that as you're driving for the first 10-15min you want to keep the RPM's as low as you can. If your engine and transmission are not warmed up enough they will not perform well at high RPM's and may even be damaged as a result of being pushed too far if they are not warm enough.