Hello,
If you switch to a synthetic gear oil, are you stuck with always having to use it? Or can you switch back? I recently went with a synthetic up front and out back, (Valvoline 75-90 GL-5) and now I notice a slight hummm while coasting at a lower speed around right hand corners. I also added 2 bottles of the BG LS II additive. The dealer is keeping it for a few things, and their going to check on it, but I thought I'd run it through you guy's (and gals)

Any thoughts would be greatly appreciated!