Lotus advise that you use nothing but Castrol TAF-X in your gearbox.
MT-90 seems a popular choice but it has never been tested or failed the tests Lotus put it through which is why isn't not the recommended lubricant. The gearbox is very specific in it's requirements when mounted in an Esprit. The low temperature performance of the lubricant is very important and it also has to withstand the extreme high pressures that the cwp contact areas will put it through. TAF-X was the only lubricant that fulfilled the criteria.
Don't argue with me, argue with Lotus!