How to fix a sticky cold weather lock?

So my rear drivers side door lock sticks in the locked position. Actually, it *functions* just fine, it just has enough resistance that the automatic door unlock system can't unlock it. Locking is fine, and one can unlock it by hand. This is the second winter it's been happening, and when I tore the door apart this summer for other reasons, I cleaned everything up, and greased what I thought needed to be greased in order to fix this problem. Apparently I failed, because it's happening again.

Does anyone know what the likely cause is? Could it actually be the locking/unlocking motor? Like I said, it locks just fine in all weather, but it struggles to unlock in cold weather.

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

Dangit... It started happening again. *sigh*.

Maybe this will have to go down in the log of permanent quirks of my car, alongside having to pull the key 1/8 an inch out of the ignition in order to turn it to the run position

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

If you say you did clean and lube all the locks not too long ago, then I would go along with your feeling and say maybe it is time to pull the motors and give them a good strip, clean and lube, they are probably gummed up with 20 years worth of crud, a good strip, clean and lube should have them running at full strength like new again.

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E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.