Let's hope that you are right. I'm fairly certain I put Redline 75w90 in the rear two years ago. But I'll change it this weekend probably. I know the mount is made for the 240, which is why I checked and compared all of the clearances. That all seemed okay, but the sound didn't start for almost a week after I put that on.
Here's to hoping it is a wheel bearing, although I've never heard a wheel bearing sound like this before. Thanks, Bernie!