The level of zinc in the Gearbox increases up to 100ppm. Different sources are possible like paintings, brass, zinc plated. Neverthelees not all the models of Gearbox nor oils show the same behaviour.
Is it possible some oils react with the metals depending on temperature or conditions? How can affect this level of Zinc to the proper lubrication or oil properties? Any test recommende to find the source and the impact on the oil?