Can I use 75w instead 70w gear oil?

[930.engineering]

I just went through this fiasco wondering why I couldn't use 75w90 gear oil vs the 75w80 my manual transmission calls for. Molakule should chime in here but you really need to stay with a GL4. I ended up buying redline MTL which is a 75w80 and is made for manual transmissions.

Because 75W-90 is almost twice as thick at relevant operating temperatures compared to 75W-80.
Not only at 100°C (which very most manual gearboxes will never see), but also near freezing point.

 

[mightymousetech]

I forgot to note: I live in Europe (Bosnia). Cant find any 70w here. not even in dealership!

I believe the BOT 303 mentioned above was the same transmission fluid my old Smart car used to take. Might be able to source something from Mercedes.

Edit: Redline MT-LV is supposed to meet BOT 303 spec.

http://www.redlineoil.com/mt-lv-70w75w

Maybe look into that more?