I recently purchased 2 XL motors from Lego direct. I noticed one of the motors has a higher pitched sound, almost a slight grind. It spins up faster and slows down slower than the other XL motor which sounds smooth and stops quicker. Has anyone noticed differences between one motor to the next? When direct coupling motors without a differential one motor will be straining more than the other which can't be good.

I am curious if I should contact Lego about this noise and speed variance between the two.

I got a new xl motor recently and it seemed smoother/more quiet/faster compared to older one but that must be from wear-and-tear on the old one. I'm sure all motors have some slight differences but not enough that you should be worried...

I think they forgot the grease on the gears. Contact Lego they will sent you another moter.

They can ask to return the defect one.

when i get a new xl motor in my hands i Always open it and put a few drops of oil inside the planetary gear boxes.

this way they are much more quiet and i think more efficient.

I too recently bought two XL motors, and noticed some differences between them. One runs smooth, and the other one has a more high pitched sound to it. However, in time, after many hours of usage, you can be sure that they will even out

when i get a new xl motor in my hands i Always open it and put a few drops of oil inside the planetary gear boxes.

this way they are much more quiet and i think more efficient.

Oil is like acid for lego parts. The only lubricant that should be applied to Lego plastic and rubber is normal silicone spray. Not oil, not vaseline, not grease etc, but silicon spray. Everything else has traces of a petroleum-like substance, which eats through plastic and rubber given enough time.