Im sure your local dealer will sell it but may cost you a few body parts.
Another option is check on Castrol's site

https://applications.castrol.com/oilselector/en_gb/c/search

I've a vague recollection that the BMW stuff is/or used to be Castrol anyway.
No doubt someone more knowledgeable will be along with other ideas/comments soon.

 

Castrol Just lists engine oil, my mate has some redline 75-90 gl5 that's left over from his Saab so hoping that will be suitable as it's mega stuff

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Castrol Just lists engine oil, my mate has some redline 75-90 gl5 that's left over from his Saab so hoping that will be suitable as it's mega stuff

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Thats strange as that site lists engine, gearbox, diff, brake & steering fluids for my car.
It shows Castrol Syntrans B 75W for my gearbox.

 

Does it kind of judder and want to come out of the gear? If so, i kind of have this issue sometimes, I say sometimes but it's happened around 2/3 times in the past where I've tried dropping from 5th to 4th and it goes mental. My cars on 14k.

 

Hi all,
Does anyone know what gear oil I need for a 14plate 125d? Got a synchro issue going down to 4th when warm and hoping a gear oil change will help it although I doubt it will cure it fully. Also has anyone else had any issues with synchros in the f21/f20 platform? Car is only on 36k so seems strange that's it's gained a bad synchro

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Does it kind of judder and want to come out of the gear? If so, i kind of have this issue sometimes, I say sometimes but it's happened around 2/3 times in the past where I've tried dropping from 5th to 4th and it goes mental. My cars on 14k.

Occasionally but I think that's just if the car is mid dpf regen on mine. I get a nice crunch currently if shifting down to 4th gear, all others are fine and can go up into 4th fine too. Dropped the oil today. Was full of metal fillings and the gear oil was a merky metallic black. New oil in and a good drive and it doesn't suffer the 4th gear issue as often but it's still present so I've been shifting to 3rd and missing 4th to try and keep the gearbox in one piece for a bit longer whilst I save up. Noticeably quieter now with fresh oil and goes between gears much nicer!

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