Can you use atf in a manual gearbox specified for sae80 gear oil?

Using ATF (Automatic Transmission Fluid) in a manual gearbox that specifies SAE 80 gear oil is generally not recommended. ATF has different additives and viscosity characteristics compared to traditional gear oils, which may not provide adequate lubrication or protection for the gearbox. It's best to adhere to the manufacturer's specifications to ensure optimal performance and longevity of the transmission. Always consult the owner's manual or a professional mechanic for guidance on fluid compatibility.