Hello I am trying to change the oil in the transmission. Does anyone know what kind goes in it or a substitute that will work that is available in the USA. The manual that I bought says SAE 90 EP oil, Example Castrol Hypoy 90. I cant find any anywhere and everyone at these part stores and transmission shop look at me like I’m crazy when I ask for that. Thanks:slayer:

I don't know the full range of oils available on your side of 'the big pond', but Penzoil make a gear oil for cars and light commercials which will probably be fine---"Penzoil Platinum 75W-90" Penrite also do gear oils (Penrite 80-90). The gear-box level/fill plug van be a real bugger to get out as it can be VERY tight. It is a 13mm square, so try using a 1/2 drive, 13mm/1/2in socket on it, the wrong way round, and then put a 1/2 in drive bar into the socket---or if you can obtain one, a proper 1/2 plug removal tool. The correct level for the gearbox is when it just starts to come out of the level/fill plug (which is situated between the drive-shaft and the bell housing on the right side (YOUR passenger side) of the gear-box.:bang:

Is that synthetic or regular on the penzoil. I can’t seem to find it when I look it up.

If I’m able to run 80-90 weight will this Lucas one work?

As I mentioned before, I don't know much about what is readily available in the USA, but the "Pennzoil 75W90 Platinum Gear Oil" comes up on their web-site. Another oil, which is for manual 'transaxles' is Red Line's "Red Line MT-90 75W90 GL-4 manual transmission oil" they also list oil for manual transaxles (which the Fiat has--gearbox and diff combined). It might be worthwhile finding out if you have a VW workshop in your area and see what they put into the VW transaxle (the older air-cooled 'classic' V/Ws):bang:

I discovered that the oil in the Fiat 126 gearbox needs to be different to the oil in a 500.
Issues around reactions with the metals is cited...apparently the bronzes need different protection . I use an American product sourced in the UK.

A lengthy discussion is had here, some light reading

https://www.fiatforum.com/500-classic/315636-gearbox-oil.html?315636=#post3149168

It identifies the issues with EP vs Non EP and the brass in the later gearboxes.

Ok please HELP. Will either of these be the right oil for the transmission according to what the manual says.

The one on the right will be exactly correct in an original, non-synchromesh ("crash") gearbox as found on the Fiat 500.