Do you hear the whirring noise when coming to a stop from a steady highway speed? For example, do you hear it when approaching a red light at a highway intersection after running at the same speed for a while? Or when decelerating (coasting or braking) after any steady run?

Ed

 

I hear the noise the worst when I am going a steady 40 mph.

 

You can buy gear oil with the friction modifier already mixed. You can use that to top up without worrying about changing the concentration.

 

+1 I have used Royal Purple in all my LS rear ends since 1996 and never once had a problem.

 

Thanks for that info, I can probably get some at autozone right? I might end up taking my truck to the dealership within the next week though for this whirring noise I am getting. It sounds like it is coming from the front end, but I have no clue where.

 

Wrong. Stay OUT of the zone.

 

where should I go then? I always go there because it is the closest.