This page is made up of my own experiences and cullings from the Xpower forums and Two sixties forum.
MG-R recommend 150k miles or 10 years and some dealers will not change it sooner as they claim it will invalidate the warranty.
However Dreadnought (MG and TVR dealer in Scotland) say that the TVR Cerbera with a very similar axle really needs an oil change after 1000 miles as the running-in leaves the oil very contaminated.
The TVR, SV/SV-R and the 260 all use the same rear axle just with different ratios which are Dana Australia final drive units which use Mobil SHC 80W140 ID as OEM fill.
Other oils approved are:- in this unit are Castrol SAF-XJ and Morris Lubricants Lodexol XFS.
There is no magic in these oils but they are the best (not the cheapest) and should be available from dealers of Aston Martin, Morgan, TVR and MG.
TVR use Dana M76 final drive and recommend oil change every year due to prolonged periods when the vehicle is not used causing condensation etc. to contaminate the oil. I guess this is worth thinking about if you don’t drive your pride and joy much. TVR have apparently used this unit for 10 years and in this time the manufacturing processes have become cleaner resulting in less running in swarf being generated.
MG however uses M80, a newer design but on the same theme as M76 and Hydratrak will not contaminate the oil. All the gears on the M80 are said to have a coating to help bedding in and although it is good practise to replace the oil at 1st service, it is not absolutely necessary. This is why the oil has a black/ grey look when 1st drainedNotes:
1) Oil should always be changed after a long track day as degradation of the oil occurs at high temperatures (165 deg +)
2) Bedding in is crucial to a long and quiet life, the pressures in the 38 mm offset Hypoid gears is greater that seen in most FWD or RWD applications, so take it easy for the 1st 1500 miles or so and you will be rewarded.3) The advantage of the 38mm offset is a very strong gear design; this is apparently how Lotus Carlton got away with M76 7.75" unit when the rest of the world was using 8.5" - 9" gears.
I will be changing my diff oil at it's 10,000mile service.