[Gav]

I thought the additive thing was a load of crap until I was trying to work out why my newly rebuilt LSD didn't feel right, it was kind of notchy when it was driven around at low speed, it was really noticeable when I was manoeuvring around in the pits at Winton one year.
Anyway I added a bottle of Penrite diff additive to the diff and it was immediately apparent that that was what the issue was.
Jag's may be different but a BorgWarner 75 LSD needs it.