I have a 1990 N/A 5 speed Manual JDM.
I Use Caltex Easy Shift 75W-90 GL3 as per the manual (SW20) that came with my car.
Hard to get but I went to Caltex South East Hampton Park (Melbourne) and ordered 2 lots of 4lt. ($103) I couldn't find it in any retail outlets and I tried a few. (Caltex stations,Bursons,Repco,Autobarn,supercheap auto to name but a few.
I "suggest" you use the correct manual gearbox oil and not the auto oil.
It is also supposed to be GL3 rated, which is a lot harder to find now. Most oils now seem to be GL4/GL5. Understand that the additives in the new oils also "may" create issues with syncros in older cars such as ours.
My gearbox is still working fine...no issues at all and has just done on 190.000 Ks.
I considered Nulon , Redline , and a cple of others but in the end kept it simple....
And now my friend, the first rule of Italian driving. Whatsa behind me (breaks rear view mirror off and tosses it behind him), is not important!
M튆àR 2