The Cat d6r does not change direction with cold oils. Goes well in the direction you choose first but does not change direction until the oil warms up. What is the 3 clutch pressure with the transmission in neutral?
Welcome to HEF Johannesterv ! Cat gurus will need a serial number.
It always helps, especially in the case of the D6R there are no less than 45 different models on the market........!! Transmission pressures are not measured in neutral. Questions for yo in the meantime: What type of oil (grade & viscosity) are you using.? When was it last changed.? When was the transnmission filter last changed.? When was the magnetic screen/filter for the transnmission pump suction last removed and cleaned.?