It's not only lubing the guides. Actually, everything should be cleaned - in time there's grit and dust settling everywhere around where the window is moving and it puts strain not only on the guides but also on the regulator motor. When you change the guide, you will have to clean all the guides and also the slits where the window is moving in the door itself. Then, try to use some Einszett or similar to keep the rubber clean and renewed. Lube and clean all the little pullies as well - whatever is moving.

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Stable: e92is, e46 M54B25, e83 N52, e53 N62 - sold, e39 M54B30 R.I.P.