Note Redline offer three differering synthetic oils in the 75W90 category.
GL5 is quoted on the bottle as being suitable for LSD axles as it has the necessary friction modifiers. I use this in my Roadsters axle.
NS (non slip) for situations where the LSD requires minimal/no slip so often used in race applications.
MT a GL4 spec oil for manual transmissions - it appears on back of bottle this is 75W80 grade though and the one I use in gearbox.
GL-5 was the one I used, however when it was drained out after a year and 3000 miles it was very dirty - silver grey colour. Which is making me think there could be a problem with the diff.
