I want to change the oil in the manual gearbox of my '84 5000s. It's all nasty and foamy, and I don't believe in that "sealed for life" nonsense. Aluminum is slightly porous....oil can get out, water can get in.
What brand/type/weight oil should I use in it? Thanks!

 

this has been disscused , https://www.audiforums.com/m_410289/tm.htm , the same will do for you too, thats what i will put in my car when i get around to it ... because I also shrare your view on the for life stuff