I've been reading up on gear oils... Apparently, the incredibly tiny contact area between two teeth can generate localised hot spots where the instantaneous temperatures can exceed 1000c. With that in mind, there are additives in gear oils which somehow turn into a liquid metallic substance which actually behaves like a lube. It takes those high temps to metallise the additives. Apparently, the oil simply vapourises over 600c potentially exposing metal to metal. It's the additives that take over for the localised hot spot lubrication. All clever stuff this gear oil. And depending if you use angle bevel, hypoid bevel or hyperboloid bevel gear oils, the metalising additives are quite different.... So there is the viscosity (like 80/90 or 70/80), there are the additives (GL-4 or GL-5) and there are the base lubricants which can be a mineral or synthetic oil. I still think that the thicker the lube, the better properties it'll have to fight friction. Just like your mate says Skezza- use a synthetic 80w90. I think he's right. The new oil I have for my box is the same viscosity (80w90) and it's GL5 or something- super, extra, extreme heavy duty. As used in tractor diffs. I have no idea what the shifting will be like when it's cold- that thick oil needs to get squeezed out of the way before the synchromesh can engage, to select a cog. I'll phone the local VW dealer in the morning for a price and ETA on that seal. I've found someone in Holland who has stock for about 5 euros. But then I'd need to wait and pay airfright. I want to see how well the EGR changes work this weekend if poss. i wonder if there is a complete gear stick linkage overhaul kit available.......