Transmission noise is like a humming or a rubbing?

Hello,

I'm hoping to get some advice from the forum experts. My 2005 Honda CRV, 60,000 miles, started with this noise coming from the transmission about 3 years (20,000 miles) ago. The noise is like a humming or a rubbing and is more noticeable when the engine is running but the vehicle is stopped. It is also quite noticeable when advancing at low speeds (less than 15mph).

Even though the transmission seems to be working fine, the dealer told me some time ago that this probably meant that the transmission would be failing at some point but they could not tell how soon. Because inspecting the cause of the noise involves taking the transmission apart, which is quite costly, they suggested that I keep driving it this way and see what happens with time.

After the 3 years have gone by, the transmission keeps working fine but I have noticed that the noise is a little louder than before. I went to a shop that specializes in automatic transmissions and just from listening to the noise they told me that changing the turbine and the filter would probably get rid of the noise but they would not be completely sure about this until they took the transmission apart and see if there is any other damage. They are suggesting a refurbished turbine as a new one would be too expensive. They are also telling me that they would be replacing the oil, and that this might run the risk of the new oil, being thinner than the current old one, causing some further damage (?) They explained that this old oil might be filling in some gaps inside the transmission parts and by replacing this oil with new oil those gaps would no longer be filled and therefore some damage could be caused - does this make any sense?

Anyway, I am not sure what to do here. Should I do nothing and keep driving until something major happens, which might not even happen at any point? Should I go ahead and replace the turbine and filter as they are suggesting? Is there any risk of having the turbine replaced with a refurbished one?

I plan to keep this CRV for at least another 5 years so I would greatly appreciate any comments that you can provide.
Thank you.