Using Your New LSD
All of the following differential fluids are fine to use: Penrite, Liqui Moly, Redline, Castrol, Motul and Mobil 1 75W140 or 75W90 (ball-bearing diffs) fully synthetic lubricant. Fill the E30/E36 differential until lubricant drips from the top fill point. If new clutches and bearings have been fitted, change the oil after 3,000Ks and then as per normal intervals beyond that. Friction modifiers should not need to be used. Contact me if you feel the need to use these, and you are not experienced with how to use them properly. In most cases I will adjust pre-load and lockup mechanically versus using friction modifiers.
In Japanese LSDs (Cusco, Kaaz, OS Giken) the manufacturer's lubricant should be used in these unless specified. Wavetrac and MFactory helical LSDs use standard oil.
Differential break-in is not required for most differentials. The clutches I fit have been lightly abraded before fitment, to ensure they do not reach high temps initially. Drive normally. Go for a short drive to ensure proper lubricant curculation through the LSD before tracking the vehicle.
Limited slip differentials have wheelspin in certain circumstances. If wheelspin occurs on the road, lift off and allow the wheel to gain traction before re-applying power. Do not allow one wheel to spin too fast, or too often. This will burn the clutch plates very quickly. Wheelspin should only occur on very uneven/wet/snowy road surfaces or if one wheel lifts off the road. Excessively stiff rear swaybars can cause wheelspin too. If your LSD is spinning one wheel on level road surfaces, you have a problem with your LSD and it should be rebuilt and/or built specifically to suit your application.
Servicing the LSD
Your new LSD will need and oil change around once per year for road and track-day cars, and as often as every few races for dedicated race vehicles. Race cars may require more frequent clutch replacement. Differential cooling fins have only a slight effect on differential temps. They are better than nothing, but an active setup is much better. An active oil cooling system with a pump and radiator can prolong differential life and reduce operating temps dramatically.