Volvo Repair: Rear Differential?, voden, rear diff

Question
Chris,
I've recently started using my '92 245 for cummuting.  It has about 170k miles.  My oil change guy said the rear diff is dry.  I've noticed a "whirring" noise.  What's involve in the fix?  One mechanic said that it doesn't NEED to be fixed.  He said that it will likely be fine dry.  What's your take?
Thanks in advance,

Chris in NH

Answer
well if your in southern NH then I would seek a professional opinion. I have a dear friend in Hudson, who is an excellent volvo tech. VODEN 603-598-9150 ask for Dennis.  You should not drive a differential dry, it needs lube, to keep the bearings from seizing up. as to the whirring noise, possible that its only a carrier bearing for the driveshaft. if you schedule an appointment with dennis, tell him chris from maine sent you.  he is a good guy, knowledgeable, and priced fairly.