Jeep Cherokee (Liberty) CRD

I own a 2004 Jeep Cherokee (Liberty) 2.5CRD with a 5 speed manual gearbox.

Please can someone advise what oil is used in the gearbox? Received conflicting advice from dealers, some say ATF fluid others Castrol Syntrax 75w90 synthetic gear oil????

In case you are interested, MPG around town is 26mpg and motorways 29mpg; good torque and power spread. I use to own 2003 2.8CRD auto; very litle difference other than better mpg, ave 23mpg.

Email if you want any further info on car.

Thanks

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