Personally I wouldn't use the ZC75 in that gearbox - ZC75 (EP, synthetic) is for the later-type 'top change' gearboxes, like the Tipo and the late Mk1/Mk2 Uno Turbo or 1372cc versions, or for that matter, the Selespeed gearbox in my 156.
For the type with the tin cover over the selector on top and the vertical bellcrank/two gearchange rods under the floor, used on most Unos '84-'94, you need ZC90, which is non-EP and not synthetic.
If ZC90 isn't available, my next preference would be Castrol VMX (80-weight, non-EP, mineral gear oil), and if that's not available, the engine oil you mentioned will be OK, especially if you add a gearbox-oil-additive to improve the shift feel. These are sold under all sorts of names, the one I use is Australian (Nulon).
If you've already put the ZC75 in, it will probably be OK, but it isn't the same as the ZC90 that's intended for the older gearboxes. You could take the view that being a newer design of oil, it works properly in all older and newer gearboxes.
But EP oils did exist back when the Uno gearbox was designed and they deliberately weren't used in front-wheel-drive transaxles to avoid the detrimental effects on phosphorous-bronze synchroniser materials. Also, my experience with the Tipo box (which had an EP oil specified, EPYX80) is that EP oils produce a grey sludge over time which gums up the gearshift. Even in modern cars with EP oil I still change my gear oil every couple of years to prevent this. I haven't had that problem with non-EP oil.
At the end of the day, it's more important that it has oil, rather than not having oil! I expect thousands of Unos are driving around with almost no oil in the gearbox, it having leaked out through the driveshaft seals.
-Alex
For the type with the tin cover over the selector on top and the vertical bellcrank/two gearchange rods under the floor, used on most Unos '84-'94, you need ZC90, which is non-EP and not synthetic.
If ZC90 isn't available, my next preference would be Castrol VMX (80-weight, non-EP, mineral gear oil), and if that's not available, the engine oil you mentioned will be OK, especially if you add a gearbox-oil-additive to improve the shift feel. These are sold under all sorts of names, the one I use is Australian (Nulon).
If you've already put the ZC75 in, it will probably be OK, but it isn't the same as the ZC90 that's intended for the older gearboxes. You could take the view that being a newer design of oil, it works properly in all older and newer gearboxes.
But EP oils did exist back when the Uno gearbox was designed and they deliberately weren't used in front-wheel-drive transaxles to avoid the detrimental effects on phosphorous-bronze synchroniser materials. Also, my experience with the Tipo box (which had an EP oil specified, EPYX80) is that EP oils produce a grey sludge over time which gums up the gearshift. Even in modern cars with EP oil I still change my gear oil every couple of years to prevent this. I haven't had that problem with non-EP oil.
At the end of the day, it's more important that it has oil, rather than not having oil! I expect thousands of Unos are driving around with almost no oil in the gearbox, it having leaked out through the driveshaft seals.
-Alex
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