i have replaced clutch master cylinder slave cylinder , clutch recon and filled box with mineral oil 80w 90 but theres ep additives in the oil the motor factor insisted it was the right oil as he worked for a fiat dealer in the 80 s 90 s and has been in the trade for years.
ive only recommisioned the car this past week driving today and there is a metalic noise out of the gear box
i also had to replace the sigot shaft seal thats why i had to drain the box any suggestions on the noise

I don't have any personal experience to share but I do know from reading the Network 54 website that the X1/9 gearbox is fussy about the oil it likes. The people on that forum always recommend Redline MTL which is 70W 80 and synthetic.

i read that but the parts lad dismissed it and swore blind thats the proper oil i used pain in the arse this car is givin me

Is the noise in every gear? I have Redline in mine and it is very smooth. Are you sure the spigot shaft seal housing is not damaged, could be scraping on the shaft if its out a bit, its made from very light tubing !

tony she only makes noise in 3rd and the box was very reluctant to go back in on the shaft we had to mate the engine and gearbox out side the car and still was very difficult there s no vibrations but can be difficult to change down to second i guess the clutch needs adjusting we want to go to mondello next week

It sounds to me that first and foremost your clutch is dragging, making it tricky to slip between gears and this can be very hard on the synchros so you need to get that sorted first and soon.

The correct oil is actually a flat 90 grade but and 80w90 is just as good for most purposes. The Redline oil (MTL or MT90) works so brilliantly well that it doesn't make much odds which you use - you can even use their shockproof gear oil which is about a 120 grade (technically it is a grease not an oil), it will work just as well, especially if you are putting more torque through the box than it was intended for. There is a reason why it is so highly regarded, especially in motorsport - it provides a tangible difference and improvement to stock oil grades.

The metallic noise (I'm guessing a slight ringing) is usually down to insufficient oil level and has more to do with noise damping than anything else.

If it sounds like metal being chewed apart then it probably is exactly that and it will be worth dropping the box and opening it up. If in doubt drain the gearbox down and check for a metallic slurry coming out - if it does then you need to drop the box and get it sorted (or replaced), if not then it is probably just insufficient oil.

The usual cause for the slurry appearing is the use of EP oils in the box - these can destroy the internals in an amazingly rapid time but equally a failed synchromesh or gear can do the same once the metal fragments have been chewed up and turned the internals into shrapnel. The Redline oils are EP rated but do not contain the same aggressive chemistry that normally appears in EP gear oils.

If the motor factor sold you an EP oil for an X1/9 gearbox he needs to be taken to task. The slightly later Tipo type gearbox (fitted in the later Uno Turbos and pretty much everything afterwards) does use an EP oil but anything earlier than that is strictly non-EP.