8.8" differential oil loss

[SSBN633]

I bought my 2005 GT used last summer with 15K miles; now at 19.5K. In 2005 the limited slip gears were replaced with 4.10. This weekend, my rear axle seemed to be noisier that I was accustomed to, and as I had planned to do a drain & refill anyway (preventative maintenance) I got ambitious and did it.

• Capacity is supposed to be 2qts 75-140 synthetic + 4oz "Additive Friction Modifier.")
• The actual drain was maybe slightly more than a quart!

Inspection found no visible signs of leakage or excessive venting. The magnetic fill plug had about a 3/32" of micro-debris (no particles or filings). The cover was sealed with gray RTV only and I reinstalled it with the recommended gasket. My actual refill capacity was the 4oz friction additive and 2-1/4qt. Result: rear axle noise was totally eliminated.

Question: what experience are others having with 8.8" axle / differential oil consumption / loss? (Rate of loss? Cause? Corrections?)

[SVT10th]

My guess is that it was improperly filled when the gears were changed. Especially if there weren't signs of it leaking...