Dave
As ever a superb article on the rare art of oils. You will recall that I have just upgraded to the Red and Grey Roadster and interestingly enough the previous owner replied to my letter with some background on the car. He kindly told me that he had some noise from the rear diff at some stage which was cured with a double dose of friction modifier. He also recommended an annual change of diff oil in this car, so I will put my new skills, thanks to your post, to good use. Further, have you found any problems with the rear diff oil change, I believe it is very viscous.
