I decided to change the bevel box oil to Redline Heavy Shock Oil. The box is a "new" one changed recently because the original box was a super whiner. Car is early 2012 and have tolerated box for some 11,000km hoping there might be some improvement. New box is better but still whines loudly. Doesnt pass the wife test, who wont do longer trips anymore. Even with earplugs and helmets on
Old box had breather at top with a tube leading up and over to exit under right hand side wood frame near rear wheel. New box has breather on side with no breather tube. I wanted to check the box so i did the "take out seat back etc method". Jacked rear and supported on axle stands Removed center floor plate Removed drain plug, collected oil in plastic basin Removed red breather/fill plug and concocted a funnel and pipe to allow filling. Put a little oil in and waited till it showed at drain. Original oil drained was about 300g Put plug back in and tightened. Started adding oil, lot by lot, waiting between each lot. I added approx 500g in total. Enough to almost reach the fill. As the car was still on the stands and in a heads down attitude i left it at that. Thought i would run for a few Km and recheck level Also assess if the new oil makes a difference noise wise, especially if it delays any temperature increases which increase the whine.
If this does not help too much, i was given a contact who does nothing else but rebuild diffs. I broached the possibility of a rebuild to better tolerances , new bearings etc. He confirmed the first step of using Redline, then to keep running for a while to establish a wear pattern. He could then strip and see what could be done.
