The drivers door on my 1995 Chevrolet van has been trouble, since I got it. The keyhole turns, but the latch on the edge of the door is miserable sluggish. I've tried WD, Silicone, white lithium, atf, and gosh knows what else. Tried cleaning it with brake cleaner, etc.
What's a good lubricant that lasts more than a week? I spray it with stuff, cycle the inside lock button up and down, and the lock frees up. A week later, it's nearly impossible to open from outside with a key (the latch part is sluggish).
I think the last time this happened, different vehicle, I had to take the latch out, and scrub it with hot water and brush and oven cleaner, to clean it all out. Can't remember what I used for lube.
What works?